Hi,
Welcome to the community!
So, okay. I did say “You don’t need a license to test on commercial editions” but that was specific to that thread’s context, which was testing localization - i.e. web rendering.
In your case, where what you want to test is rendering of a custom metric in a branch context, you will need a license because (also from that thread):
And you’ll need to run analysis to get your metric calculated for the branch.
Unfortunately, I don’t see a good path forward here except to shell out $150 for a Developer Edition license.
HTH,
Ann