Use the camera app on to scan the QR code on the back of your dot card.
A link should pop up which will take you to the dot profile.
Using the tap feature on iPhone 7, iPhone 8, iPhone X and older requires one extra step. The NFC scanner in the control center must be used.
Make sure your phone is updated to iOS 14.
dot cards can not be scanned while:
the flashlight is ON
the phone screen is OFF
their phone is in Airplane Mode