I have to put in the admin password if i run the installer so it's running with admin rights, i have no antivirus active and the installer installs it and shows that it's working
That's exactly the problem I explained before: if you are required to enter a password, it's because your user doesn't have admin rights, so you are now running the installer as as DIFFERENT user ( the administrator, not you ), which means the installer is setting the required registry keys to another user (the administrator, not you), so when you run the program, the keys are not found in your user registry, making the menu not working.
If, instead, your regular user account has already admin rights, the installer will just *use* them when it runs, so it will set the registry to your user, which is the same as you run the program with.
You can try changing the properties for Addon Manager\Couatl64\Couatl64_MSFS.EXE to run As Admin.
If that doesn't work, your only option is just GIVE your regular user Admin rights, and run the FSDT Universal Installer again, so it can create the correct registry keys in your normal user account.