Wasn’t there a need to have a specific version of Win10 or later loaded for this to work?
I assume you’re using Win10? Have you updated it to the latest rev? Have you installed the XBox app and signed in to your Microsoft Account?
There’s a whole bunch of things that have to work here. I had an issue with my sign in that was preventing my updating the game. I think it got screwed up when my first attempt at install burped and it corrupted my sign in. I had to uninstall the store and the xbox app and reboot and reinstall and it finally allowed me to update. The apps showed I was signed in, but FS2020 didn’t recognize that I was. Some sort of bug with the store/xbox app that reinstalling fixed. I imagine a corruption of some files in the inaccessible winapp directories/registry.