Lucity's Web Map Gallery displays the webmaps available to the current user. If the user is logged into his or her ArcGIS account, the Gallery displays all of the public maps and any maps assigned to the user. If the user is not logged into his or her ArcGIS account, only the free maps are shown.
Administrators control the individual maps that a user can access through the Portal. This section of the Lucity Web Help Guide explains how to control which maps appear in the gallery on a wide scale.