To use TRIPP lying down, you must be in Recline mode. To get into recline mode, follow these steps:
Open the TRIPP app.
You will see 5 icons at the bottom of the TRIPP home/main menu
Click the settings (gear icon), and this will allow you to select and toggle on recline mode.
When your experience loads, find the position that feels just right for you and press B to realign your view.