Getting this error on the kiosk?
Lists have different permission settings when it comes to public check-in methods like the kiosk and public check-in link.
The permission settings can prevent a new profile from signing in if they are not already on your profile database.
How to turn on open registration on the iOS app:
Tap on a list from the My Lists screen.
Select the grid icon (top menu bar).
Select List Details
Scroll down to Registration
Set the toggle to Open
(see screenshot below for reference)
How to turn on open registration on the Dashboard:
On My Lists page, hit the three dots next to a list.
On the List Details page, scroll to the Check-in Settings section.
Toggle Open Registration to YES