Design Software - Hard To Learn, Harder To Learn
When I started 3D printing (don't get me started on that at the moment) I started using FreeCAD, found it frustratingly complex, tried OpenSCAD, and something of the mathematical approach (you code your designs in the openSCAD language) of that really appealled to me. I've been using that tool ever since but thought I really should learn a proper CADware. I can't afford Fusion360 (and WON'T pay rent for software), and the free version is too limited. So, it's back to FreeCAD. Fortunately, there is a video tutorial that explains it quite well.
So, if you're tired of the big brands' gouging you and leaving you unable to work when they dump older hardware, but there's no download that'll continue to work with your hardware. If you want to pay less for software, generally (do support open source with cash or code where you can, though), then OpenSCAD and FreeCAD are the wares I recommend and use. Give them a try.