Download file after filling a form
Instead of creating different webforms for each file, you could just have one form that can handle this. Here is my suggestion:


Make all links to your whitepapers to load a webform and pass the filename as a parameter for your webform. You can then store that on a hidden field on the form. 
Create a custom submission handler for your webform to trigger a download upon submission (use the filename from the hidden field on the form).