Push Notification with FCM + Spring Boot, SenderId mismatch error

I'm doing a project using Spring Boot to send notifications to my React Native app. Since I'm using Expo to my React Native app, I did a different configuration following this tutorial and tested with Notifications composer from Firebase and worked well.

For the Spring Boot, I used this another tutorial to configure FCM, also I create a Private Key file from SDK admin in Firebase to use here:

try {
    FirebaseOptions options = FirebaseOptions.builder()
    .setCredentials(GoogleCredentials.fromStream(new ClassPathResource(MY_PRIVATE_KEY_FILE).getInputStream()))
    .build();
    if (FirebaseApp.getApps().isEmpty()) {
        FirebaseApp.initializeApp(options);
    }
        } catch (IOException e) {
             e.printStackTrace();
        }

So I did a method to send the message using token from Server Key like this:

private String token="AAAAm_p0hoc:************************************";

public void sendPushNotificationWithData() {
    PushNotificationRequest pushNotificationRequest = new PushNotificationRequest();
        pushNotificationRequest.setMessage("Send push notifications from Spring Boot server");
        pushNotificationRequest.setTitle("test Push Notification");
        pushNotificationRequest.setToken(token);
        Map<String, String> appData= new HashMap<>();
            appData.put("name", "PushNotification");
        try {
            fcmService.sendMessage(appData,                 pushNotificationRequest);
        } catch (InterruptedException | ExecutionException e) {
            e.printStackTrace();
        }
}

But I'm just having this response from FCM:

POST https://fcm.googleapis.com/v1/projects/myproject/messages:send
{
  "error": {
    "code": 403,
    "message": "SenderId mismatch",
    "status": "PERMISSION_DENIED",
    "details": [
      {
        "@type": "type.googleapis.com/google.firebase.fcm.v1.FcmError",
        "errorCode": "SENDER_ID_MISMATCH"
      }
    ]
  }
}

I tried to make a new project into FireBase, update the private and server keys but still having the same response.

Is something I forgot to set up or am I doing it wrong?