This howto just works for Steam users since it has a dedicated Family accounts feature.
When buying via Microsoft Store, I did not see any such feature yet other than signing in with the same XBox account (which is possible for different windows accounts).
So all users need to sign in to the same XBox account, the one where the game has been registered with.
my kids are 16 and of course we are cautious regarding what they do on the computer. But I can’t stay close to them for hours when playing FS2020. And for security issues, I don’t want to let my account open to my teams, with my docs, etc…
Just used steam as example, the family accounts are on Windows. You just need to copy a MSFS shortcut for each account on the computer and then have them start MSFS and sign into their profile (top right of main menu) from their computer account on the computer.