For iOS users, there is a couple ways to pair your 

 with the App: HomeKit pairing and Mysa pairing.

Mysa recommends using a 2.4GHz network with speeds of at least 4Mbps or higher.  2.4 GHz is better for products like Mysa that must travel through walls and all around your house. 2.4 GHz has a better signal range, which means more coverage around your home. 

If the Mysa is not showing in the Apple Home App:

The registration code for each Mysa thermostat is located in two places. You can find it by either:

How to pair your Mysa with either iOS or Android using the Mysa App

Mysa Pairing

Why is my Mysa not connecting to my WiFi network?

HomeKit Pairing

HomeKit Pairing

How to pair your Mysa for Electric Baseboard Heaters V1 & V2 with Apple HomeKit