https://www.pcgamer.com/forza-horizon-4-was-downloaded-four-months-early/

Forza Horizon 4, which is taking a road trip to the UK, was available to download on the Windows Store over the weekend, at least for some people, despite being 4 months away from release. Unfortunately for those able to download it early, they weren’t able to do anything with their new game. 

The Forza Twitter account mentioned the unexpected early download yesterday, admitting that it was not unintended and that the full game will download automatically when it’s released.