Short answer run flame from startApplication:
/opt/Autodesk/flame_2020.3.1/bin/startApplication
You can just navigate here and run startApplication by double clicking on it. This will launch flame for you and keep a terminal open showing you all of the feedback from the launch and log any error messages.
Long answer. I’ll start another thread @johnag
I found this Launch Flame on Mac from a Terminal @johnag