How to prevent my DAW to auto-trigger the Scaler 2 pattern?

I’ve loaded Scaler 2 on a MIDI channel in AUM on iPad. The purpose is to route the midi from my hardware keyboard through Scaler to play a chord on a AU synth when I press a piano key. This in itself works fine.

But when I press Play in AUM, Scaler automatically plays the current pattern (without me pressing a key). How can I prevent this?