This might be basic, but this works for me:
@editable
RoundSettingsDevice : round_settings_device = round_settings_device{}
# Runs when the device is started in a running game
OnBegin<override>()<suspends>:void=
Print("we've started")
RoundSettingsDevice.RoundBeginEvent.Subscribe(OnRoundBegin)
OnRoundBegin():void=
Print("round has begun!!!!")