There is a figurine on the app menu (to the upper left on iOS and to the upper right on Android). You click this icon to create an account, which will require an e-mail address and password.
Now go to the menu and select Departures or Departure times. Click the magnifying glass (to the upper right for iOS and to the lower right on Android) and in the menu select stops or stops. In the search screen, enter the initial letters of your favorite stop. If multiple stops are then listed, select the one of your choice. Now, click the star icon to the upper right (Android) or the plus sign icon to the upper right (iOS). The stop is then added to your favorites. This is how you subscribe to information about the entire route. (Of course, you must allow the app to send messages).