Which Core Addon Apps (or modules) are required to run the OA Builtin Apps?

New user of Drupal/Open Atrium, would appreciate guidance on which Core Addon Apps (or modules) are required to run the OA Builtin Apps. Apparently OA Related Content is used to add topics to OA Discussion? Without Related Content, error was posted (in Apache log) about Base Table Not Found and content was inaccessible. After OA Related Content is enabled, icons are displayed under content pane and content is accessible after Publish.