Google Play Game Services App Crashes after successful authentication in Unity android

I am making a multiplayer Unity3D Game. I am using play game services plugin from Google given the link below https://github.com/playgameservices/play-games-plugin-for-unity I am in a strange trouble, so far I am testing and running the minimal Sample that ships with the free Google Play Game Services for Unity. In this sample there is only a simple button that authenticate user with GPGS. Upon pressing the button in my minimal example that I have taken from the Plugin the app does authenticate myself and my picture also displays as texture below button but then the app crashed and below I copied log that I get when app crashes.

12-07 13:08:48.924 23694-23694/? E/AndroidRuntime: FATAL EXCEPTION: main Process: com.gs.toughashell, PID: 23694 java.lang.Error: FATAL EXCEPTION [main] Unity version : 5.2.2f1 Device model : LGE LG-F240L Device fingerprint: lge/omega_lgu_kr/omega:5.0.2/LRX22G/1506717071d79:user/release-keys

I am also confused in one think. For iOS while testing IAP and other stuff our app doesn’t need necessarily appear in the iTunes Connect for testing. Is there is the same case with google? I mean for testing purposes do I need to upload my apk to the alpha/beta testing mode in the apk section of google play developer console? Or I can test it without uploading just as in iOS??