> (you sign away all rights to the things you made free)

I don't see that in Autodesk's terms, which (per quick search - not exhaustive) seem to apply to "Fusion for Personal Use":

https://www.autodesk.com/company/terms-of-use/en/general-ter...

The only license I can find it compels is "If You provide Autodesk with ideas for improvement, suggestions, or other feedback".

(Not a lawyer, not your lawyer, not legal advice etc. etc.)