Enable Single User Access
Select Projects in the top navigation. Then click the title of the event you wish to have single user access
Expand the General menu on the left and click Access Control.
Using the toggle on the top right, ensure Enable Single User Access is turned on
Turning on Single User Access
How Single User Access affects users
When Single User Access is Enabled and a second attendee tries to login with the same credentials as another. The first attendee will be taken to the login page and presented with the below error