Connecting is easy - simply download the app and it will walk you through the connection procedure. GE SmartHQ is a free smartphone app. And, yes, either an iPhone or Android are compatible. It is also compatible across many GE appliances and works with Alexa and Google Assistant.
Simply download and install the app to your phone and register, accept terms and conditions, etc and then add the module to your indoor unit. Adding the module is as simple as opening up your indoor wall unit and inserting it into the dongle slot provided. You will need one module for each indoor unit you may want to control. For example, if you have a more than one system in your home, you will need a module for each system.
Once everything is installed, simply follow the prompts on your phone to finalize the pairing. You must complete your initial set up at home through your home's wireless connection.