Click the admin dropdown and choose Atlassian Marketplace.The Manage add-ons screen loads.
Click Find new add-ons from the left-hand side of the page.
Locate TechTime CSS Switcher Plugin via search.The appropriate add-on version appears in the search results.
Click Try free to begin a new trial or Buy now to purchase a license for TechTime CSS Switcher Plugin.You're prompted to log into MyAtlassian. TechTime CSS Switcher Plugin begins to download.
Enter your information and click Generate license when redirected to MyAtlassian.
Click Apply license.If you're using an older version of UPM, you can copy and paste the license into your Confluence instance.