You must allow installation from unknown sources in your device's settings before you can install the Rummy 777 APK. Usually, to accomplish this, go to your device's security settings and check the box next 888 slotsto "Unknown Sources.". ****. Setting up the APK file for Rummy 777. You can install the Rummy 777 APK file on your device after enabling installation from unknown sources. Locate the downloaded APK file in the file manager on your device, then tap it to start the installation process. Once the installation is complete, you can use your mobile device to play Rummy 777 APK by following the on-screen instructions.