I need something like that, and i would like to know if its possible or now with the current release.
Visitors will be able to to view the all files and categories. But when they will be able to download only if the file category allowing that. Some files will be free because and other files will be vip, premium etc. (but they should be able to see the file informations even vip, premium, just they cant download)
Visitors or members will be able to see all content.
Your plugin will decide to let him/her download or not depending the permissions of the category of ile when visitor click to download button. And it will show popup screen that says "Please purchase a membership ...." if the file is not for visitors,
i hope i could have tell what i need.