File sharing setup to share large files with remote contractors?

So I have a home setup and I am currently having to upload videos to Dropbox and Google Drive to share them with remote contractors. Unfortunately the file sizes are massive, (mostly raw and 4K video) and I have a lot of them so the above solutions are slow, expensive and inefficient as they have to re-upload the final editing videos so that I can access them.

So my first thought was instead of Google Drive or Dropbox or such, I'd just use regular old drive sharing or NT userids/passwords to allow access to the contractors to various bits of a server instead of having to upload everything elsewhere first. I bought a box for video editing, it has two external drives, a very fast one and a very stable one. Raw video and all the necessary video assets are located on the fast one, and are backed up to the very stable one, with the editing software on the box itself. Given it would take a bunch of time to upload to Google Drive or Dropbox, I'd rather just give someone access to what they need to do the job, then they can upload the edited video directly to me.

Is there any open-source/self hosted solution for such a setup?

What is the best setup/software to use for this?