Enqueue scripts not working with if is page conditional tag in functions.php

Try doing in the opposite way. Add_action can always be active, and add the if statement into the function. Like this:

add_action('wp_enqueue_scripts', 'insert_mapsvg_scripts');

function insert_mapsvg_scripts() {
  if( is_page( 37629 ) ) {
    wp_enqueue_style( 'mapsvg_css', site_url('/mapsvg/css/mapsvg.css') );
    wp_enqueue_style( 'nanoscroller_css', site_url('/mapsvg/css/nanoscroller.css') );
    wp_enqueue_script( 'mousewheel_js', site_url('/mapsvg/js/jquery.mousewheel.min.js'), array('jquery'), '', true );
    wp_enqueue_script( 'nanoscroller_js', site_url('/mapsvg/js/jquery.nanoscroller.min.js'), array('jquery'), '', true );
    wp_enqueue_script( 'mapsvg_js', site_url('/mapsvg/js/mapsvg.min.js'), array('jquery'), '', true );
  }
}

Also, as @marktruitt commented. Generally JS is stored in the plugin or theme folder. If it's a custom theme an enqueue may look like this:

wp_enqueue_script( 'mousewheel_js', get_template_directory_uri(). '/mapsvg/js/jquery.mousewheel.min.js', array('jquery'), '', true );

Whereas if you're using a child theme it would look like this:

wp_enqueue_script( 'mousewheel_js', get_stylesheet_directory_uri(). '/mapsvg/js/jquery.mousewheel.min.js', array('jquery'), '', true );