In the JavaScript file "firebase-messaging-sw.js" make the following adjustments by pasting the configuration:
Example
/* ... */
const firebaseConfig = {
apiKey: "<<Firebase apiKey>>",
authDomain: "<<Firebase authDomain>>",
projectId: "<<Firebase projectId>>",
storageBucket: "<<Firebase storageBucket>>",
messagingSenderId: "<<Firebase messagingSenderId>>",
appId: "<<Firebase appId>>",
measurementId: "<<Firebase measurementId>>"
};
/* ... */
JS