If you have added visitors to an access group, or deleted/edited visitors of an access group, or changed access levels of an access group, you have changed the access group's settings. In these cases, you should apply the changes to the connected visitor terminals to make the changes take effect.
Make sure you have added access levels for visitors. See Add Access Level for Visitors for details.
Make sure you have added the visitor terminal to the platform. See Manage Visitor Terminals for details.