1.) go to https://console.firebase.google.com/

2.) Select you project or Click -> Add project to create new project

3.) Select gear icon (1), select "Project settings" (2) and select "Cloud Messaging" (3). "Firebase Cloud Messaging API (V1)" (4) must be Enabled
If "Firebase Cloud Messaging API (V1)" not Enabled - go to Google Cloud Console, select you project, select "Library" section, search " Firebase Cloud Messaging API" and Enable it

4.) Go to "General" section, and you can see "Project ID" (1) and "Project number" (2)

5.) Open "sys/config/db.inc.php" config file and set constant "GOOGLE_SENDER_ID" value from "Project number" and set constant "FIREBASE_PROJECT_ID" value from "Project ID"

6.) If you have previously configured Google Cloud Storage, Cloud Vision, OTP in your project and created and uploaded a “service account file” to the server, skip steps 7 and 8

7.) You need service account file on you server side. Go to "Project settings" (1)(2), tab "Service accounts" (3), click "Generate new private key" (5)

8.) Downloaded json file copy to server side folder "js\firebase" (Dating App) or "public\js\firebase" (My Social Network or TkReels)