Can't get texts from smartapp

Added smartapp Left it open. Added my phone number for getting alert but nothing happens. Sensor correctly shows open closed but no notifications received. What am I doing wrong

US Customers: You must opt in to receive SMS from SmartThings. You can do this by texting YES at any time to 844-647 for each phone number set up to receive SMS.

that is… if Left it Open still works

Automations might be a better choice