From this tab the name of the Media Library can be changed as well as a description of the types of files that are available. The default name of the media library is the same as the group name but doesn't need to be. A teaser image can also be uploaded to replace the default icon used for the Media Library.
The Security tab is where the Group Admin will decide who has the ability create,delete,modify or view files/folders within the library. By defualt only Group Admins have full access to the media library and additionally group members can view the content. These settings can be changed to provide group members access to create,delete or modify files and folders or any registered member.