Run Time error 13 VBA Excel

I hope you are well I have some code see below. Essentially what it does is allows a user to upload two workbooks and it performs a Vlookup. The Macro was working fine until the sheets went from 65,000 to 280,000 rows. I first got the error 'run time 6 overflow' so I changed

Dim intLastRow As Integer  

to

Dim intLastRow As Double

That is when I got the Run Time error 13 on this line of code

.Range(.Cells(2, extraCol), .Cells(intLastRow, extraCol)).Value = Application.WorksheetFunction.VLookup(.Range(.Cells(2, 1), .Cells(intLastRow, 1)).Value, Consent.Sheets(1).Range("B:J"), 8, False)

I know diming intLastRow As Double has created a mismatch but do i dim intLastRow As Doubleas something else or do i amend the code else where? Any help would be greatly appreciated. the rest of my code is below.

Sub Add_consent()

    'Definition of used variables
    Dim Directory As String 'Directory for inputs and outputs
    Dim Consent_folder As String 'Directory for inputs and outputs
    Dim inputFile As String 'Input file name
    Dim currentInput As String 'Input file name
    Const DELIMITER As String = "|" 'Values delimiter
    Dim OutputFile As String 'Output file name
    Dim lngCount As Long    'selected files count
    Dim wbkOutput As Workbook 'output workbook
    Dim wbkTemp As Workbook 'temporary workbook
    Dim myWkBook As Workbook 'Input Workbook
    Dim Consent As Workbook 'Consent file
    Dim Consent_name 'new opened file
    Dim myWkSheet As Worksheet 'Input Worksheet
    Dim sheetNum As Long 'Variable for sheet number
    Dim sheetNames() As String 'output worksheet sheet names
    Dim sheetInterfaceName 'Sheet name representing DID interface
    Dim Active As Worksheet 'Active worksheet
    Dim intLastRow As Double 'Last Row Element
    Dim Error_Codes As Worksheet ' Sheet containing error codes
    Dim myRecord As Range 'Record for output
    Dim myField As Range 'Cell value for output
    Dim nFileNum As Long 'Variable for file number
    Dim sOut As String 'Text to be written into file
    Dim invalidDelete As String 'Case of invalid delete attempt
    Dim sheetIndex As Long ' Current sheet index
    Dim Selected As Long '
    Dim rwCount As Long 'Number of current sheet rows containing data in tracking file
    Dim colCount As Integer 'Number of current sheet columns containing data in tracking file
    Dim extraCol As Integer 'Number of current sheet columns containing data in tracking file
    Dim indexRow As Long 'Row index
    Dim helpRow As Long '
    Dim AddIn As Integer
    Dim selectedCount As Integer
    Dim int1 As Long
    Dim int2 As Integer
    Dim int3 As Integer

    'General application settings
    Application.ScreenUpdating = False 'Turns off switching to exported excel file once it gets opened
    Application.DisplayAlerts = False 'Turns off automatic alert messages
    Application.EnableEvents = False '
    Application.AskToUpdateLinks = False 'Turns off the "update links" prompt

    'User prompt, choose HCP file
    MsgBox "Choose HCP/HCO file missing consent information"

    'Alternative way to open the file
    Dim fd As FileDialog
    Set fd = Application.FileDialog(msoFileDialogFilePicker)
    fd.AllowMultiSelect = False

    'Assign a number for the selected file
    Dim FileChosen As Integer
    FileChosen = fd.Show
    If FileChosen <> -1 Then
    'Didn't choose anything (clicked on CANCEL)
        MsgBox "No file selected - aborted"
        End 'Ends file fetch and whole sub
    End If

    Dim fss As Object
    Set fss = CreateObject("Scripting.FilesystemObject")
    inputFile = Dir(fd.SelectedItems(1)) 'parses only the name of file
    Directory = fss.getParentFolderName(fd.SelectedItems(1)) & "\" 'parses only directory of the file

    'Open HCP file .xlsx spreadsheet
    Set wbkTemp = Workbooks.Open(Filename:=Directory & inputFile)
    'Set wbkTemp = Workbooks(Workbooks.Count)

    'Get number of columns in the HCP file
    colCount = wbkTemp.Sheets(1).Cells(1, Columns.Count).End(xlToLeft).Column

    'Get the number of rows in the HCP file
    intLastRow = wbkTemp.Sheets(1).Cells(Rows.Count, 1).End(xlUp).Row

    'Set GCM_ID format to number
    wbkTemp.Sheets(1).Range(wbkTemp.Sheets(1).Cells(2, 1), wbkTemp.Sheets(1).Cells(intLastRow, 1)).Select 'Specify the range which suits your purpose
    With Selection
        Selection.NumberFormat = "General"
        .Value = .Value
    End With

    'Prompt user for the second file
    MsgBox "Select file(s) containing Consent information"

    'Open Consent file dialog
    Dim filedial As FileDialog
    Set filedial = Application.FileDialog(msoFileDialogOpen)

    Dim chosen As Integer
    chosen = filedial.Show
    If chosen <> -1 Then
    'Didn't choose anything (clicked on CANCEL)
        MsgBox "No file selected - aborted"
        End 'Ends file fetch and whole sub
    End If

    'Number of selected files
    selectedCount = filedial.SelectedItems.Count

    'Extra variable
    AddIn = 0

    For Selected = 1 To selectedCount
    'Open file with Consent info
    Consent_name = Dir(filedial.SelectedItems(Selected))
    'Consent_folder
    Workbooks.OpenText Filename:=Consent_name, StartRow:=1, DataType:=xlDelimited, ConsecutiveDelimiter:=False, Tab:=False, Semicolon:=False, Comma:=False, Space:=False, Other:=True, OtherChar:="|"
    Set Consent = Workbooks(Workbooks.Count)

    'Number of rows in consent file
    rwCount = Consent.Sheets(1).Cells(Rows.Count, 1).End(xlUp).Row

    'Specify the column to paste data
    extraCol = colCount + AddIn + 1

    '1)
    'VLOOKUP across spreadsheets for consent data
    'wbkTemp.Sheets(1).Cells(1, 1).Copy
    'wbkTemp.Sheets(1).Cells(1, extraCol).PasteSpecial Paste:=xlPasteFormats
    'wbkTemp.Sheets(1).Cells(1, extraCol).Value = "Consent"
    'With wbkTemp.Sheets(1)
        '.Range(.Cells(2, extraCol), .Cells(intLastRow, extraCol)).Value = Application.WorksheetFunction.VLookup(.Range(.Cells(2, 1), .Cells(intLastRow, 1)).Value, Consent.Sheets(1).Range("B:J"), 8, False)
    'End With

    '2)
    'VLOOKUP across spreadsheets for consent data
    'wbkTemp.Sheets(1).Cells(1, 1).Copy
    'wbkTemp.Sheets(1).Cells(1, extraCol).PasteSpecial Paste:=xlPasteFormats
    'wbkTemp.Sheets(1).Cells(1, extraCol).Value = "Consent"
    'With wbkTemp.Sheets(1)
    '    '.Range(.Cells(2, extraCol), .Cells(intLastRow, extraCol)).Value = Application.WorksheetFunction.VLookup(.Range(.Cells(2, 1), .Cells(intLastRow, 1)).Value, Consent.Sheets(1).Range("B:J"), 8, False)
    '     For int1 = 2 To intLastRow
    '        if Application.WorksheetFunction.IsNA(Application.WorksheetFunction.VLookup(.Cells()))
    '
    '     Next int1
    'End With

    '3)
    'VLOOKUP across spreadsheets for consent data
    wbkTemp.Sheets(1).Cells(1, 1).Copy
    wbkTemp.Sheets(1).Cells(1, extraCol).PasteSpecial Paste:=xlPasteFormats
    wbkTemp.Sheets(1).Cells(1, extraCol).Value = "Consent"
    With wbkTemp.Sheets(1)
        .Range(.Cells(2, extraCol), .Cells(intLastRow, extraCol)).Value = Application.WorksheetFunction.VLookup(.Range(.Cells(2, 1), .Cells(intLastRow, 1)).Value, Consent.Sheets(1).Range("B:J"), 8, False)
    End With

    'Close the file with consent information
    Consent.Close

    'Loop again for next file
    AddIn = AddIn + 1
    Next Selected

    'Deal with N/A values
    With wbkTemp.Sheets(1)
        For int1 = 2 To intLastRow
            For int2 = 1 To selectedCount
                If Not Application.WorksheetFunction.IsNA(.Cells(int1, colCount + int2).Value) Then
                    .Cells(int1, colCount + 1).Value = .Cells(int1, colCount + int2).Value
                End If
            Next int2
        Next int1
    End With

    'Remove extra columns
    With wbkTemp.Sheets(1)
        .Columns(fnColumnToLetter_Split(colCount + 2) & ":" & fnColumnToLetter_Split(extraCol + selectedCount)).Delete Shift:=xlToLeft
    End With

    'Save and close the new workbook
    With wbkTemp
        'Save and close the new workbook
        .SaveAs Filename:=inputFile
        .Close True
    End With

    MsgBox "Available consent information added"


End Sub

Function fnColumnToLetter_Split(ByVal intColumnNumber As Integer)
    fnColumnToLetter_Split = Split(Cells(1, intColumnNumber).Address, "$")(1)
End Function