1. Go to your phone’s Settings
2. In Settings, tap on Security, Applications or Additional Settings. Your device may have a slightly different name for this.
3. In Additional Settings, tap on Privacy as shown in the image.
4. Then click on Install Unknown Apps
5. Please click on “ Allow from this Source “, as shown in image :
6. You have now enabled downloads from outside the Google Play Store. To find an app to download, use Google Chrome or your device’s stock browser to search for and download the APK of the app you want.