Ring App Missing "Sensors" or "Security Devices" to Install Motion Sensor / Detector

I have set up a Ring Alarm Pro system. I try to add a motion sensor. The setup instructions say: "In the Ring app, tap Menu, then tap Set Up a Device, then tap Security Devices, then tap Sensors, and tap Motion Detector.". In my Ring App (Android on Pixel 8 Pro) there is no "Security Devices" menu, so I cannot set up the device. What is going on?