You can install Unstoppable via the Atlassian Marketplace. Administrators can find and install apps from Marketplace in the apps administration pages as follows: 

Administration Settings 

  • As a system administrator, navigate to the application's administration console and click "Add-ons".

Find the Add-on

  • Under Manage Add-on Section, click the "Find new add-ons" link.

Search for Unstoppable in the Marketplace 

  • Type "Unstoppable"  in the search box and hit "Enter"Click "Free Trial".