Build in feature of push notification is using the Firebase. Below a brief description how to prepare project.
Need to open firebase console, need to add project.
Need to add the name of the project
When is created, need to open project settings
At cloud messaging tab, may find server key, need to copy this.
Push notification settings you may find at the administrator dashboard >> Settings >> Push notifications. Open this setting and paste server key in Private Api Key
Get the rest of the settings. Go back to the first tab at the firebase console, and tap the button show at the box "Your apps"
Add nickname of the app and register it
After that you be able to see the data
Copy the values to the push notifications settings.
Before save, enable.