Microsoft has never ported Forza Horizon to Android or iOS. The closest official releases are:
Theoretically, apps like (Wine for Android) can run very old Windows games. However, Forza Horizon 3 requires DirectX 12 and powerful x86 emulation — no Android device today can emulate it at a playable frame rate. Expect < 1 FPS. Forza Horizon 3 Android Apk Obb Download
Websites offering an "Android APK" for Forza Horizon 3 are distributing fraudulent software. These downloads are often used to spread: Microsoft has never ported Forza Horizon to Android or iOS