The Push plugin requires that your Android application project is set up with the Google Play Services SDK, and that devices have the Google Play Services APK.
The Push plugin will automatically set up the Google Play Services. However, for additional details on setting up Google Play Services, see Setting Up Google Play Services.
Open the Google Developers Console.
Click Create Project to create an API project.
Enter a project name and click Create. A page displays your project ID and project number.
Record the project number for later use as the GCM sender ID.
Enable the Google Play Services.
In the sidebar on the left, select APIs & auth.
In the displayed list of APIs, turn the Google Play Services toggle to ON.
In the sidebar on the left, select APIs & auth > Credentials.
Under Public API access, click Create new key.
In the Create a new key dialog, click Android key.
In the resulting configuration dialog, supply one SHA1 fingerprint and the package name for your app, separated by a semicolon. For example, 45:B5:E4:6F:36:AD:0A:98:94:B4:02:66:2B:12:17:F2:56:26:A0:E0;com.myexample.
To get the value for the SHA1 fingerprint, follow the instructions in the console help.
Record the API key for later use to perform authentication in your application server.