There are two ways to use the Captions Teleprompter.
Captions Camera
Tap on Create > Teleprompter
Type or paste your script from your clipboard
Choose Captions Camera
Choose Scrolling (one continuous scroll) or Scenes (start and top recording)
Tap Record
Tap on the icon on the top right to switch between Scrolling and Scenes.
Push Notifications
Tap Create
Tap Teleprompter
Type or paste your script from your clipboard
Tap Enable Push
Tap Record
To ensure you receive the push notifications, ensure you have disabled Do Not Disturb and that you've accepted the correct permissions. Open your iPhone Settings > Captions > Notifications.