I'm having trouble sending Notifications with the FCM Cloud Function

Question

I'm sharing my code, I've uploaded 10,000 ads, but I still don't know. I've been getting this error for a while, but all my tracks are ok.

The error I get:

ERROR: Firebase Messaging Error: An error occurred while trying to authenticate to the FCM servers. Make sure that the credentials used to authenticate this SDK have the appropriate permissions.

But;

await admin.messaging().send Multicast(message);

i receive the sent statement, but the notification does not arrive. I will also send you two different codes.

NOT WORKING

exports.sendNotificationAdmin = functions.firestore.document('ilanlar/{ilanNumarasi}').onCreate(async (snap, context) =\> {
const dataListing = snap.data();

const userTokens = \['cYZPopVmaEF9mm0KCUZLcJ:APA91bEPOKDRs6xJLLiGcHDzascKL9LGSefAy7Hfa7vmVX-76bsH4uCrWTFmhvrMpYw-4unYzcictRd5hpzgttd_AKsPpxCKFCGljysUBHe4cBYsBRcL-g7AItsMVTs6wuuOov28mF9y'\];

const isActive = dataListing.isActive;

    if (isActive == 0){
        const message = {
            notification: {
              title: 'Yeni ilan eklendi!',
              body: 'Lütfen Onaylayın!',
            }
        };
    
        try {
            const response = await admin.messaging().sendToDevice(userTokens, message);
            console.log("Bildirim Gönderildi!");
        } catch (error) {
            console.error("Bildirim HATASI:", error);
        }
    
    } else {
        console.log('isActive Değeri 0 değil.');
    }

});

working but not sending notifications :

I explained above that I tried two types of ways, but I couldn't get on one way. sendToDevice gives a permission error, but sendMulticast does not, but does not send a notification.