SUMMARY
The system is divided into separate clients, and one client cannot see another client's cabinets or folders. The only exception to this is if a site administrator is designated as a cabinet administrator for a different client, and this can only be done by an existing cabinet administrator within the client.
MORE INFORMATION
Within the client, the cabinets and folders that users can access is controlled by a combination of client administrators and cabinet administrators - the client administrators are responsible for which group each user is placed into, and the cabinet administrators decide which groups have access to the cabinet or its folders, and what permissions each group has in each folder.
Splitting the responsibilities in this way makes the system more secure - the client administrator may be able to allocate groups, but they cannot give those groups permission to see folders unless they are also a cabinet administrator.