If you have the IAQ module, you need the Redlink gateway.
See the compatibility chart here: (page 2) https://customer.resideo.com/resources/Techlit/TechLitDocuments/03-00000s/03-00658.pdf
Once you have a Redlink module, and have it connected to Honeywell TCC, you can add the thermostat via [RELEASE] Honeywell TCC Total Connect Comfort Parent/Child Drivers
