The button is anywhere you can download a customization. Try System Settings → Appearance & Styles → Colors & Themes, click on any of those pages and look in the upper right corner of the page. You should see “Install from File…” and “Get New…”.
The button is anywhere you can download a customization. Try System Settings → Appearance & Styles → Colors & Themes, click on any of those pages and look in the upper right corner of the page. You should see “Install from File…” and “Get New…”.