Firebase Cloud Messaging (FCM) is the new version of GCM. Link to Google

  • Send Payload Push 
    Please check the box before creating your app for this feature to be enabled in the app 
  • GCM API Key 
    Enter the server key here
  • GCM Sender ID 
    Enter your Sender ID (a multi-digit numeric value).

Select Save. Lastly, the app must be rebuilt so that the changes are effective in the app.