You don't need an app. You simply download the game's .apk file onto your android tablet. Double-click it, and if your tablet can support the game, it will install it.
There are two settings you need that can be found in Settings > Security and privacy (the exact name depends on your phone):
- Advanced: Install unknown apps. This setting lets you select the sources from which you can install apps. If you download the app to My Files (or similar) you can give your phone permission to install apps from there. Most phones, the first time you try to install it, will alert you that the source doesn't have permission and open the page from where you can set permission or ask you if you want to set the permission.
- Google Play and Protect (optional). If the app is not registered with Google Play Store, this feature might flag it as harmful.