Some people have stated that the ConfigUI page just says loading. If you're having this issue you must use a newer browser. Most often this happens if you have an outdated version of Raspbian. If your version of Raspbian predates Raspbian Jessie W/PIXEL then we suggest following the steps in How To Install Raspbian(full). Following this solution has fixed this specific issue 100% of the time.
Have a different issue? Take a look at the Troubleshooting Page.