This is my experience installing MSFS 2024 on Xbox X.
TL/DR - after first run, quit MSFS, reboot Xbox, and check for updates, then launch MSFS 2024 again. You will get an update for MSFS 2024 Addon Support, which is presumably needed for WASM… I’m not sure if came from checking Xbox updates, or just relaunching MSFS.
Once you have the Addon Support, then the Premium, Deluxe, and Premium Deluxe aircraft become available (streamed).
Probably everyone is going to need to read the new official Controller FAQ:
Install was a smooth experience so far:
I had factory reset my Xbox (removing MSFS 2020) because I like to test everything “as new”. No issues downloading MSFS 2024. I had pre-purchased the Premium Deluxe. The download was 11 or 12 GB.
Upon first launch, there was a bit of a delay as the installer unpacked everything. Then there are a few set up screens to choose your avatar, and to acknowledge any peripherals it finds connected. In my case an Xbox controller, and a Microsoft keyboard and mouse.
As expected the Marketplace says “coming soon”.
In the Marketplace tab there is “My Library” which shows all previous purchases such as World Updates with a “streamed” tag, which means no option / need to download or install. Interestingly it also shows the Premium Deluxe content and planes as “streamed”.