CAD file to GDML

Dear users,

I am looking for a way to convert CAD files, specifically STEP, into GDML (I work on Ubuntu 20.04.4 LTS). I found the following:

The problem is that it requires FreeCAD v0.15 or v0.16 and I am only able to install v0.18 which apparently runs on python3.

Has anybody used this tool before and can help me with it? Or does anybody use a different tool for converting STEP into GDML?

Thank you in advance for your time