How to generate a resume after an applicant submitted an online resume?
I would create a profile type using Profile2 module and call it something like 'Resume'. So that every user can create a Resume profile for themselves. 

Then I would install Print module and enable Print PDF and set it to show up on Resume profile pages.

You must play with the permissions so that only the owner of the profile can access the profile page and the PDF version. You may have to write some custom code to make PDF version accessible only once. You may achieve this writing an access callback function for the PDF path.