That's because Unsigned APK need patched device, otherwise it cannot be installed.
[Videotutorial] How To Login With Google+ Or Facebook App On Modded Games - Platinmods.com - Android & iOS MODs, Mobile Games & Apps
How To Login With Google+ Or Facebook App On Modded Games A. For Facebook-Login you just need to remove your Facebook App from the device (even Facebook Lite)! NOTE: On some Emulators you cannot remove Facebook Lite, it will install automatically again. Install Luckypatcher and choose...