cap production deploy error Net::SSH::AuthenticationFailed: Authentication failed

http://www.sitepoint.com/deploy-your-rails-app-to-aws/

I was following this tutorial to deploy my Rails app to Amazon EC2 until I got to the end where it told me to do this:

cap production deploy

When I type that into the folder where my code is, I get this error :

** Invoke production (first_time)
** Execute production
** Invoke load:defaults (first_time)
** Execute load:defaults
** Invoke bundler:map_bins (first_time)
** Execute bundler:map_bins
** Invoke rvm:hook (first_time)
** Execute rvm:hook
** Invoke rvm:check (first_time)
** Execute rvm:check
DEBUG [be2a201f] Running ~/.rvm/bin/rvm version as [email protected]
DEBUG [be2a201f] Command: ~/.rvm/bin/rvm version
cap aborted!
SSHKit::Runner::ExecuteError: Exception while executing as [email protected]: Authentication failed for user [email protected]
/Users/Minling/.rvm/gems/ruby-2.2.1/gems/sshkit-1.7.1/lib/sshkit/runners/parallel.rb:16:in `rescue in block (2 levels) in execute'
/Users/Minling/.rvm/gems/ruby-2.2.1/gems/sshkit-1.7.1/lib/sshkit/runners/parallel.rb:12:in `block (2 levels) in execute'
Net::SSH::AuthenticationFailed: Authentication failed for user [email protected]
/Users/Minling/.rvm/gems/ruby-2.2.1/gems/net-ssh-3.0.1/lib/net/ssh.rb:239:in `start'
/Users/Minling/.rvm/gems/ruby-2.2.1/gems/sshkit-1.7.1/lib/sshkit/backends/connection_pool.rb:50:in `call'
/Users/Minling/.rvm/gems/ruby-2.2.1/gems/sshkit-1.7.1/lib/sshkit/backends/connection_pool.rb:50:in `create_new_entry'
/Users/Minling/.rvm/gems/ruby-2.2.1/gems/sshkit-1.7.1/lib/sshkit/backends/connection_pool.rb:22:in `checkout'
/Users/Minling/.rvm/gems/ruby-2.2.1/gems/sshkit-1.7.1/lib/sshkit/backends/netssh.rb:187:in `with_ssh'
/Users/Minling/.rvm/gems/ruby-2.2.1/gems/sshkit-1.7.1/lib/sshkit/backends/netssh.rb:137:in `block in _execute'
/Users/Minling/.rvm/gems/ruby-2.2.1/gems/sshkit-1.7.1/lib/sshkit/backends/netssh.rb:133:in `tap'
/Users/Minling/.rvm/gems/ruby-2.2.1/gems/sshkit-1.7.1/lib/sshkit/backends/netssh.rb:133:in `_execute'
/Users/Minling/.rvm/gems/ruby-2.2.1/gems/sshkit-1.7.1/lib/sshkit/backends/netssh.rb:77:in `capture'
/Users/Minling/.rvm/gems/ruby-2.2.1/gems/capistrano-rvm-0.1.2/lib/capistrano/tasks/rvm.rake:9:in `block (3 levels) in <top (required)>'
/Users/Minling/.rvm/gems/ruby-2.2.1/gems/sshkit-1.7.1/lib/sshkit/backends/netssh.rb:54:in `instance_exec'
/Users/Minling/.rvm/gems/ruby-2.2.1/gems/sshkit-1.7.1/lib/sshkit/backends/netssh.rb:54:in `run'
/Users/Minling/.rvm/gems/ruby-2.2.1/gems/sshkit-1.7.1/lib/sshkit/runners/parallel.rb:13:in `block (2 levels) in execute'

I think I followed everything in the tutorial correctly. This is my first time using EC2, how should I fix this?

Here is my deploy.rb file

# config valid only for current version of Capistrano
lock '3.4.0'

set :application, 'studentdiscount'
set :repo_url, '[email protected]:minling/StudentDiscount.git'
set :branch, :master
set :deploy_to, '/home/deploy/studentdiscount'
set :pty, true
set :linked_files, %w{config/database.yml config/application.yml}
set :linked_dirs, %w{bin log tmp/pids tmp/cache tmp/sockets vendor/bundle public/system public/uploads}
set :keep_releases, 5
set :rvm_type, :user
set :rvm_ruby_version, 'jruby-1.7.19' # Edit this if you are using MRI Ruby

set :puma_rackup, -> { File.join(current_path, 'config.ru') }
set :puma_state, "#{shared_path}/tmp/pids/puma.state"
set :puma_pid, "#{shared_path}/tmp/pids/puma.pid"
set :puma_bind, "unix://#{shared_path}/tmp/sockets/puma.sock"    #accept array for multi-bind
set :puma_conf, "#{shared_path}/puma.rb"
set :puma_access_log, "#{shared_path}/log/puma_error.log"
set :puma_error_log, "#{shared_path}/log/puma_access.log"
set :puma_role, :app
set :puma_env, fetch(:rack_env, fetch(:rails_env, 'production'))
set :puma_threads, [0, 8]
set :puma_workers, 0
set :puma_worker_timeout, nil
set :puma_init_active_record, true
set :puma_preload_app, false
set :ssh_options, { user: 'deploy', keys: %w(~/.ssh/student-discount-ec2.pem), forward_agent: true }
# Default branch is :master
# ask :branch, `git rev-parse --abbrev-ref HEAD`.chomp

# Default deploy_to directory is /var/www/my_app_name
# set :deploy_to, '/var/www/my_app_name'

# Default value for :scm is :git
# set :scm, :git

# Default value for :format is :pretty
# set :format, :pretty

# Default value for :log_level is :debug
# set :log_level, :debug

# Default value for :pty is false
# set :pty, true

# Default value for :linked_files is []
# set :linked_files, fetch(:linked_files, []).push('config/database.yml', 'config/secrets.yml')

# Default value for linked_dirs is []
# set :linked_dirs, fetch(:linked_dirs, []).push('log', 'tmp/pids', 'tmp/cache', 'tmp/sockets', 'vendor/bundle', 'public/system')

# Default value for default_env is {}
# set :default_env, { path: "/opt/ruby/bin:$PATH" }

# Default value for keep_releases is 5
# set :keep_releases, 5

namespace :deploy do

  after :restart, :clear_cache do
    on roles(:web), in: :groups, limit: 3, wait: 10 do
      # Here we can do anything such as:
      # within release_path do
      #   execute :rake, 'cache:clear'
      # end
    end
  end

There is this part that I'm a little confused about: (But not the cause of the error I think because I'm having this problem because of an authentication error?)

set :rvm_ruby_version, 'jruby-1.7.19' # Edit this if you are using MRI Ruby

I'm not using jruby, what should I put there instead? How do I find the MRI version?