After installing the Engage Call app onto your Android TV / Android stick/box, you'll need to connect it to your organisation, this is done via the Engage Client Management Console, for help accessing the console see our guide here.
In the Management Console, click on the "Patient Call" section
This will open the sub menu, where you can find the "Waiting Room TV" page, click that to open the pairing screen.
On this screen, enter the code from your waiting from TV, and click "Save"