Install Sonic Mania Plus and the Megamix Mania mod on your PC first to ensure they work.
Copy the entire modded game folder to your Android device's internal storage. Run via Gamehub/Container: sonic megamix mania download install android
This is an unofficial fan game. It is not on the Google Play Store, nor is it affiliated with Sega. However, Sega has historically turned a blind eye to non-commercial fan projects. As long as you own a legal copy of the base game (which you typically provide via a ROM), you are in the clear legally. Install Sonic Mania Plus and the Megamix Mania
It looks like you’re asking about a for a search term related to downloading and installing Sonic Megamix Mania on Android. It is not on the Google Play Store,
or a Windows container to run the Steam version directly on Android. 3. Finalizing the Install Sonic Megamix Mania (v0.9) - Sonic Hacking Contest