STEP 1: Create a Google Project and save the "Project Number"
1.1 Create a project at https://console.developers.google.com/project for your app.
1.2 Select your Project and go to IAM & admin->Settings. Your project number should be located on this page.
Copy the "Project Number" from this page.
You will need to add it to the source code of your app later when you follow the SDK guide.
STEP 2: Turn on "Google Cloud Messaging" API
2. Under APIs & Services>Library, search for "Google Cloud Messaging". Turn it on.
STEP 3: Create and save Server Key
3.1 Under "APIs & services" > "Credentials", click "Create credentials".
3.2 Select "API key"
3.3 Press the "Create" button.
DO NOT enter anything into the box.
3.4 Go to https://console.firebase.google.com and import your google project
3.5 Click to "Project overview settings" and choose "CLOUD MESSAGING" tab. Copy Server Key.
STEP 4: Send your GCM credentials to Gravitec support
4.1 Send your Project Number(Sender ID) and GCM Server key to email@example.com.