I have implemented a simple chat using Twilio conversations API. I'm following the doc for web push notifications (https://www.twilio.com/docs/conversations/javascript/push-notifications-web) and it's not clear to me what "FCM SECRET" I need to include in my Twilio Credential. I have tried with my firebase app key pair (public and private) and also with firebase web API key, but in the Twilio logs I allways get a GCM/FCM unauthorized error: GCM/FCM API key is revoked or invalid error.

Update:

My app code:

import { initializeApp } from "https://www.gstatic.com/firebasejs/9.8.2/firebase-app.js";
import { getMessaging, getToken, onMessage } from "https://www.gstatic.com/firebasejs/9.8.2/firebase-messaging.js";

const firebaseConfig = {
    apiKey: "...",
    authDomain: "...",
    projectId: "...",
    storageBucket: "...",
    messagingSenderId: "...",
    appId: "..."
};

const firebase = initializeApp(firebaseConfig);
const messaging = getMessaging(firebase);

const serviceWorkerRegistration = await navigator
    .serviceWorker
    .register('/js/firebase/firebase-messaging-sw.js');

if (firebase && messaging) {

    // getting FCM token
    getToken(messaging, {
        vapidKey: '...',
        serviceWorkerRegistration: serviceWorkerRegistration,
    }).then(async (fcmToken) => {

        console.log('token', fcmToken)
        const conversationsClient = await getConversationsClient();

        conversationsClient.setPushRegistrationId('fcm', fcmToken);

        onMessage(messaging, payload => {
            console.log('Message received. ', payload);
            conversationsClient.handlePushNotification(payload);
        });

    }).catch((err) => {
        console.log('Error getting token', err);
    });

} else {
    // no Firebase library imported or Firebase library wasn't correctly initialized
}

The fcmToken is generated and successfuly registered in Twilio.

The Binding is created In Twilio with my credential referenced: