For the following steps you need Confluence Administrator permissions.
The add-on is available at the Atlassian Marketplace. To install the add-on, log into your Confluence as a system administrator and navigate to the "Find New Add-ons" tab of the Universal Plugin Manager (UPM) in the global administration. There you simply search for "SubSpace Navigation for Confluence". You can find the UPM via the menu entry "Find new add-ons" or similar. For more details about the UPM please refer to the documentation provided by Atlassian.
The add-on needs a valid license, otherwise features might not work. Valid licenses are either full licenses, renewal licenses, or 30-day trials and are available at the Atlassian Marketplace. The license model is the same that Atlassian uses for its products – for further information see the Atlassian documentation.
Image 1: Add-on Manager (click to enlarge)
To obtain a license and apply it for the add-on, please carry out the following instructions, (also see the screenshot above):
The add-on is activated in the Global Administration.
You can update your add-on to the current version directly in the Confluence administration. Go to "Manage Add-ons" and open the add-on. Click the "Update" button.