I had exactly the same problem. Nowadays MIcrosoft likes putting apps in a folder where even I as an admin on my own machine can't access properly!!!
C:\Program Files\WindowsApps\Microsoft.Limitless_1.1.7.0_x64__8wekyb3d8bbwe
I've changed ownership of the folder to myself but it still says I'm not allowed to add it "You don't have permission to open this file".
THis may be normal though as I've just tried the same with FS 2020 (C:\Program Files\WindowsApps\Microsoft.FlightSimulator_1.38.2.0_x64__8wekyb3d8bbwe) and I get the same message.