I use GitHub to authenticate. It’s easy enough and signup on GitHub is straightforward.

I use FreeCAD, Fusion, and Solidworks. I don’t love freecad as it’s unintuitive and clunky. Solidworks is powerful and okay but I often find myself fighting with it.

Fusion, so far has been the one I like most, but it doesn’t run on Linux which forces me to keep my MacBook around. The collaboration features in fusion are good and it handles step files way better than solidworks does.

I know Rhino is really good for the price, so maybe consider testing it out. I believe the licensing is perpetual.

I am by no means an advanced user when it comes to this kind of stuff but just mentioning Tailscale as an option if it fits your use case. It effectively gives you site to site tunneling with the option of zero trust controls, and is extremely simple to configure to work in what I believe is your intended use case.

I’d give it a read through and see if it works for you.