It’s a nice gesture, but this is exactly why a lot of people don’t like giving away free stuff. It’s why IT departments are hesitant to give away equipment they are throwing out because some users will come back and expect free tech support. Not saying you’re against doing anything like that, but just that asshole companies like Microsoft make this so damn difficult nowadays that doing as others suggested here to create a new Microsoft account for this is going to get you calls inevitably in the future when they forget the password or run into other issues. And if not, it’ll likely end with them not using it because of the hassle or throwing it out.
I hate to sound negative because it’s an awesome gesture on your part to do and I’m sure in a perfect world, it would be wonderful for some of the residents to get to use something like that.
But since it’s not like the old days of having a CD you pop in but a digital app connected to an online account, you’ll need to do somethings that may cause confusion. It sounds like you’d have to do as others suggest and create a new Microsoft account and have a license for that game on there. Or get a GamePass subscription on that account that would allow access to Flight Simulator and more, but that would mean a perpetual donation for them to use it too.
Someone may come along and suggest a pirated copy of Flight Simulator, but I would strongly advise against that because it can put the home at legal risk if discovered and can cause other issues like if it gets patched in the future.