Like all add-ons in Atlassian Marketplace, SLA Time and Report is set in two ways:
...
If you want to install the add-on from the Jira admin page, please follow the instructions below. (You need to be a JIRA Administrator in order to install SLA Time and Report)
1. First, click Apps menu and go to Find new add-ons page.
2. Type "SLA Time and Report" by SaaSJet in the search box and then click on it.
...