Something to verify first: Are you using the latest version of the app? (i.e Did you download the app in the last week?)
If you have then I think I know what could solve your issue:
- Go to the Home app in iOS
- Create a Home; if it is your first time setting up Homekit, clicking "Get Started" creates a Home automatically and you should be able to then go and pair your Mysa
- Try pairing the thermostat again, it should work now
If you're still having trouble with your thermostat. Please reach out to our team if you have any further questions!