Yes, first start the Include process by going into the app and Connect New Device, and then go to the settings on the thermostat and select yes to join a zwave network. While you’re at the thermostat, configure the Fan Cycler mode. I have mine set for 10 minutes on and 50 minutes off. That way the device type can manage your fan with the Circulate option.
If the thermo won’t join, try to exclude it first before trying to include it, and if it still won’t join, you may have a distance issue between the hub and thermostat.
Search the Community for how to create a custom device type, and use this code to use what I have in the image above:
https://raw.githubusercontent.com/constjs/SmartThings-Devices/master/thermostat.device.groovy