This post discusses the solutions to use when the Gaming Services app is not working for you or you can't install or update Gaming Services.

A Mobile Services Manager can be useful Having a wireless carrier control, update, or install apps on a device in the background has advantages for the average user. In practice, managing these ...

This problem became so bad that, for a time, Google decided to lock down the feature. Users can now enable the feature in Settings > Apps > Special app access > Install unknown apps.