Digital ID at TSA

Question on the process for using a digital ID at a TSA checkpoint. I know the first step is the same as Apple Pay (double tap side button, tap the reader), but what I’m curious about is the next step.

The Apple support site says you then have to acknowledge what info you want to share. Once that happens, do you have to tap again, or do you just leave your phone on the reader the whole time? I haven’t had a chance to try it myself yet, and I’m curious about the process. Thanks!