1. Download rune-forza.horizon.6.iso
2. Double-click rune-forza.horizon.6.iso to mount it, or right-click and select the Mount option
3. Forza Horizon 6 should show up as a device under My Computer - open it (double-click)
4. Run setup.exe - Check the "Copy contents of RUNE directory to installdir" checkbox before hitting Install!
   - I noticed that it creates 2 copies of the installer window but one of them is fake(visual only). Annoying, but it works.
5. You can now Unmount it from My Computer by right-click and select Unmount/Eject, and delete the rune-forza.horizon.6.iso file
6. Play the game.