Thanks for the report, Patricia.
I can confirm this issue for today's latest pkg, but also the 4.0 pkg. I'm on Catalina 10.15.7 with XCode 12.2 and Python 3.8.5. Installing v3.2 works, however.
Unfortunately, Patricia, I don't currently have any advice for you. You could - for now - install the older version 3.2. For 4.0 and latest, I think we need to fix the issue in the package.
Note for others: I also tried uninstalling first, as well as partial install (without carputils) but both fail as well.
Technical details: I have tracked the issue to the 'postinstall' scripts. I will create an issue in with all the info I found.