I seem to be having the same issue with activation as others. I went thru most of this thread and installed the Universal Installer again, Activation from the Universal Installer works, but when I enter the P3D V5.3 and select Add-On manager it shows the products I "Activated" as in "Trial mode"?
Any thoughts on how to resolve, like I said, I've tried everything mentioned here and running Win11 defender only and have firewall exception for Couatl.exe (both of them for P3D and MSFS).
Recommendations on how to proceed?
Cheers, Rob.