fixed controller

app/controllers/applies_controller.rb

@@ -2,11 +2,8 @@ class AppliesController < ApplicationController
   before_action :load_job, only: %i[new confirm create]
 
   def new
-    @apply = if back?
-               ApplyJob.new(session[:apply_job])
-             else
-               current_user.apply_jobs.build
-             end
+    build_params = session[:apply_job] if use_apply_job_session?
+    @apply = current_user.apply_jobs.build(build_params)
   end
 
   def confirm
@@ -51,7 +48,7 @@ class AppliesController < ApplicationController
     @current_user ||= User.first
   end
 
-  def back?
+  def use_apply_job_session?
     request.referer&.include?('confirm') && session[:apply_job].present?
   end
 end

app/views/user_mailer/apply_job.html.slim

@@ -15,5 +15,6 @@ p
   | Full name: #{@apply.user_name}
 p
   | Email: #{@apply.email}
-p CV:
+p 
+  | CV: #{url_for(@apply.cv)}
 p Best,