Download file after entering email address

Hello

I have a question. I need a function that will add a input field in which person will enter email address in order to download the file. The email address will be later used for newsletter sending.
Any ideas or help would be much appreciated. I was exploring Contact Form 7 and Email before Download plugins integration but I need something more dynamic because download files would be assigned to custom post types and creating a form each time would be to difficult for my client. So the key is to have something generated automatically when a file is uploaded in a custom meta box which is in a custom post type.

Thanks