Get the HE app installed on the iPhone and register it into your HE ( it should create a Mobile App device and and then select whatever triggering device you want to be notified about, motion sensor, door sensor, water leak, HSM status etc. You can have such notifications sent to both devices.
It boiled down to me not setting up the geo-fencing options. I've added them and then both my Android and iPhone became available for notifications. Notifications are working perfectly on both and were easy to setup!