I think you can try FreeCAD software, which has an A2plus workbench for easy assembly of IQ parts, and FreeCAD is a free and open source software that you can search and download directly from Google. Here is the link FreeCAD: Your own 3D parametric modeler.
One of the deciding factors for our teams in choosing a CAD software, besides ease of use or breadth of capabilities, is the community surrounding it. For VRC, our CADer likes Fusion360 because the kids learned with Fusion in school and there’s a huge set of libraries and Discord group for Vex CAD. For IQ, OnShape published a VexIQ library back in 2018, and Coach Palardy published a more recent one last year. LDCad and Bricksmith both work with the VexIQ libraries for SnapCad, which are readily available. If there are no existing libraries for a particular software/platform then it’s up to each team to build/import them, which is a big task. I don’t believe there’s an IQ library for Fusion360 or FreeCad. I’m not sure if FreeCad works out of the box with the existing SnapCad libraries.
Have CADed quite a few VIQ robots using fusion 360 and it is actually quite a good experience. For this I used this library, and just imported all the files to fusion 360 which took less than 5 minutes.
Although I do prefer Inventor, Fusion 360 is a great option.