Simple portal to upload and download documents to my server

General information for the website: Electrical support services
Kind of development: New website from scratch
Num. of web pages/modules: 2
Description of every page/module: I require a portal placed on my server.
My clients will have their own login and be able to send me documents (any size).
I then will be downloading the documents to my computer and working on them for the client.
When I have finished the job I will then upload the documents back to the server for my client to retrieve.

When my clients initially upload files they need to be able to choose and create a folder name for the files to be collected in. But they can't delete files at anytime.

When I'm uploading the finished documents I can do the same but I have full editing rights. This is so I can do a clean up of my clients document area.
Description of requirements/features: Nothing fancy, just has to work and be simple like a Wordpress configuration screen.
Extra services needed: Installation
Extra notes: