Forza Horizon 4 is leaving the Steam store, get it while you can.
There are only a few very specific ways users might have obtained the game without a direct purchase: Forza Horizon 4 Free Download (Steam Edition)
There has never been a permanent "free to keep" version of the full game on Steam. Any sites offering a "free download" for the Steam Edition are typically providing unauthorized pirated versions or scams. Rare "Free" Legitimate Methods (Past & Current) Forza Horizon 4 is leaving the Steam store,
Players who had an active, full-paid Xbox Game Pass subscription on June 25, 2024, and had purchased any DLC for the game, were eligible to receive a free game token to own Forza Horizon 4 permanently. Rare "Free" Legitimate Methods (Past & Current) Players
While the game was still active, there were occasionally free car packs, such as the Mitsubishi Car Pack, though these required owning the base game. Risks of "Free Download" Sites