I set this same thing up several years ago and it was a piece of cake. It was very simple, for personal reasons (me, on the road, my cousin in Europe, etc)
This is NOT a corporate/company setup, so it may not work for you
- WIndows 10 Pro
- Set a static IP
- Use a DNS forwarder (like NOIP.com) so that you will connect to the address (as your public IP will change)
- Port forwarding on your router to send the traffic to your file server
- FILEZILLA FTP SERVER
Then you just set up the users on your PC for the appropriate access, and FileZilla will do the heavy lifting of serving up your files
It was a really easy setup and their (FileZilla) documentation was very simple to follow.