I'm also having the error "could not find valid AFCAD..." No matter what Airport, Gate, Stand - same thing. This is beyond frustrating. I've tried everything mentioned here to no avail.
Your error is caused by a permission problem in the airport cache folder:
Error while creating airport cache: can't write to "C:\ProgramData\Virtuali/Couatl/msfs\meta.txt"
This shouldn't normally happening, because of course we set the proper permissions in the installer and we reset them correctly again each time your run the FSDT Updater, so it might be caused by:
- Your antivirus is blocking access to it. Configure the antivirus to add the whole Addon Manager folder to the Exclusion.
- The file might be blocked from a crash happened in a previous session. Restart windows, remove this folder:
C:\ProgramData\Virtuali
And run the FSDT Update again, so the correct permissions are reset.