Atlassian Companion 2.2 for Mac was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. We recommend checking the downloaded files with any free antivirus. This free software for Mac OS X was originally developed by Torus Knot Software Ltd. The program lies within System Tools, more precisely File Managers.
From the developer:
Atlassian Companion is an app that enables users to edit Confluence files in their preferred desktop application, then save the file back to Confluence automatically. The download and the re-upload of files are managed by the Atlassian Companion app, which needs to be installed on each user's machine to enable file editing.
You may want to check out more software for Mac, such as Songwriter's Companion, File Storage Companion or Landscaper's Companion - Gardening Reference Guide, which might be related to Atlassian Companion.