How to use

I've followed the prompts in the app to add an Apple TV.
However, when the activity starts, i.e., TV turns on, ATV turns on, the light on the ATV, flashes continously and nothing happens.
It's like, the ATV doesn't know what to do.

I've tried using the "Learn from the remote" feature but apparently the ATV uses Bluetooth instead of Infrared which the U1 uses?

Can someone set me straight on how to actually setup an ATV 4K correctly?