Windows 10 games on XBOX One?

I bought Forza Horizon 4 on a PC through the Windows Store. Can I play the game on the XBOX without buying a new one?

Yes, as long as you enter your Microsoft account on the Xbox with which you bought the game, it should be available for download somewhere on the Xbox

Incidentally, Forza Horizon 4 is actually an Xbox game, it is only available on PC through Play anywhere