On thing that is different about this version of MSFS is that it is not a program. It’s an app (UWP).
And you can use a custom folder. The installer gives you this choice of where to install. But after it’s installed, don’t move folder/files around. Only the “Community” folder is used for mods that is not from the marketplace. And be mindful of what add-ons you do put in there as I mentioned, some will cause issues with MSFS as the developers of MSFS do not have control on how 3rd party developers code.