Hello, got the same Problem, i activate it, and didn't "receive" the "Digital Ownership" File.
So its Unplayable, because i didnt have any Discs! or any "Digital Ownership" File. I tried everything.
Reinstalling a few times, turning off Anti-Vir and Firewall. Logging on off. Resetting the MS Store Cache. I have no more ideas!
"Known Issue: Some users seeing a "Please insert the Microsoft Flight Simulator disc" error when launching the game on Windows 10.
Workaround: In order to play the game digitally on Windows 10, you will need to have the Digital Ownership File installed as it is required to grant the necessary permissions to play. If you already have this file installed and are running in to this error, please uninstall and reinstall this file only and this should resolve the issue. There is no need to uninstall the entire 127+GB base game files. Uninstalling this small 10MB file is all that will be needed. "
and this doesnt help!