Hi, I'm quoting this rate since you've mentioned that you'll take care of the page design. So I basically give you a functional system with essential html + css. It would be fully usable but you'll need to handle the colours and designs as you like.
I see the following key functions as necessary.
1. Admin - create accounts, disable/enable accounts. This also includes a simple search feature to locate a user's account.
2. User logs in/out, change passwords.
3. User downloads files.
However, there's an important aspect to clarify... That is, how are these files held? Are they in a folder or in a DB? And what are these files about? EXE, text, DOC?
Please use the message board to clarify further.
Cheers!