“Make sure to hold your phone close to the screen and keep it still inside the outline for the entire test.”
- Close to the screen (not touching the screen, but close to it [I used about 0.4"/1 cm])
- Keep it still
- Front of the iPhone towards the TV screen
I didn’t find it easy to get it started at initial attempt either, but it does work, if you hold the iPhone just right. [I used cotton ‘art’ gloves to hold my fingertips steady against the screen at a fixed position, without causing fingerprints on the screen.] Calibrate video or audio - Apple Support
What is your model iPhone? Identify your iPhone model - Apple Support
You will need your own iPhone with Face ID support and iOS 14.5 or later and matching Apple ID account for iCloud services. iPhone models that support Face ID - Apple Support