The game is installed on the android mobile (Motorola G5_Android version 7.0) and doesn’t work just shows this.
Check logs. UE4 outputs entire logs in to Android logcat system, so you can check whats happens in UE4, but only in Devlopment build. Android SDK provides debugging tool called DDMS:
https://stuff.mit.edu/afs/sipb/project/android/docs/tools/debugging/ddms.html
It will show you all logs from the device so you need to add a filter with package name of you application. UE4 should print out crash information in logs before closing as well there should be information from Android. Without that information we can only guess whats the issue same as you.
I assume you got ADB working with your device as it will be needed to make this work, if automatic application upload to device works it means it works already, if not you need to follow those steps: