Bear in mind that I have the Store version, but I suspect that Steam will be the same, since this is "the" core folder.
C:\Program Files\WindowsApps\Microsoft.FlightSimulator_1.15.10.0_x64__8wekyb3d8bbwe
Also remember that you'll have to change your shortcut every time the sim updates to a new version.
There should be a way to take ownership of the Windows Store version folder but I have the Steam version so I'm not 100% sure. Maybe try Googling "take ownership cmd" and see what you can find if you are interested, I had to do something similar a while back when tinkering with Forza Horizon.
I already tried taking ownership of the folder but still no go
The apps folder is even more heavily guarded than the program files folder.
Proof once more that not installing in the default location is still valid!
Priller
For Store owners, paste the entire path into the Windows address bar and you'll get there. You just can't drill down to it.