Don’t bother downloading or registering
At best it offered less information than their website, at worse just took you so slow or non existent information.
I found no way to book the promised breakfast options and didn’t know I was going to receive breakfast until I bumped into the guard/conductor next morning.
In the end I got a tray of snacks and a choice of coffee and juice. It was ok, but certainly not the travellers choice of menu, time and breakfast in bed.
Just speak to the guard/conductor - they know what service will be delivered. The App was nothing like the experience offered.