The script will work this way.
Admin Side - Admin will be able to activate users, to upload and delete files.
User Side - Users will be able to register with name, email, company name and password, after this admin will receive a notification with the user details and a link to activate user.
After user activation, user will receive a confirmation email.
Users will be able to upload files to theire folder, but not to delete them or change them.
Uploads will have a progress bar with estimated time left, after upload user will receive a confirmation, and admin will receive a notification with the link to download file.
I have a simple file management php script that you can use as the base for this script.
He works like this.
Admin can create users/folders and can upload/delete files.
Users can login to upload/view files.
The upload form doesn't have a progress bar.