Hello fractal5,
Your choices are much more limited on Linux. FreeCAD is hard to grasp for some people, while others pick it up quickly. If you're having trouble installing it on Linux, I can't only recommend you join the FreeCAD forum and post about your problems, you will surely get help. You'll also get a lot of help to learn using it. There are many YouTube videos, and the Help forum is quite active.
You did not mention which Linux distribution you're using. It is much, much simpler to install and use FreeCAD on Ubuntu or derived systems like Linux Mint than on other GNU/Linux distros. FYI I'm in charge of the Ubuntu PPA repositories (we have two, "Stable Releases" and "Daily Builds").
Quote
naxem42
Onshape

I was under the impression that they stopped accepting users, since they're still in the beta testing stage.