I am using TrainerRoad with my Magnus, Stages Left only PM, and an iPhone 7. I use the Rouvy app to calibrate my trainer, and the Stages app to zero my PM. The Rouvy app also updates the firmware, so check for updates as well!
Once you spin the cranks and rear wheel, the Magnus and Stages will wake up and TrainerRoad will automatically connect to them. By default, PowerMatch will be enabled, and I think it works quite well.