Purchase the plugin on the Official Unreal Engine Marketplace.

In the Epic Games Launcher, the plugin will appear in your Library.
Go to the Library tab and find the plugin and add it to the engine.

In Unreal Engine, the plugin will be available in the plugins section.
Go to Settings -> Plugins -> Search for "Play Base Services" and ensure it is enabled.

Go to the Plugins Configuration in Project Settings -> Plugins -> Google Play Base V2 and tick Enable Google Play Services V2.

This toggle allows this plugin as well as our other plugins (Saved Games and Events) to detect the upgrade and adapt appropriately.

Follow Google's documentation to make sure you have setup Play Games Services. A Guide on how to do so can be found here.

NOTE: When the documentation speaks about using your SHA1 fingerprint for your Android credential, make sure you use the one generated for you in the Google Play Console. You can find the correct one by navigating into your application within the Google Play Console and in the left navigation menu, go to "Test and Release" / "Setup" / "App Signing".

Make sure to use the "App Signing Key Certificate" SHA-1 fingerprint