1. Download the app's APK file from a above-mentioned reputable source.
2. Make sure you trust the source of the APK file. Enable "Unknown sources" on your Android device by going to Settings > Security > Unknown Sources. This allows you to install apps from sources other than the Google Play Store.
3. Use a file manager app to navigate to the location of the APK file on your device.
4. Tap on the APK file to begin the installation process. You may see a warning message about the potential risks of installing apps from unknown sources. Read the message carefully before proceeding.
5. Follow the on-screen instructions to complete the installation process. Once the installation is complete, you can open the app from your app drawer or home screen.