401 Page does not exist

I’ve used this plugin many times without issue but his one puzzles me. The installer.php and archive files have been uploaded to the /sbcu directory. In fact, if you navigate to this URL https://www.apolloinsuranceservices.com/sbcu/ you will see the files, however, it still throws a 401. Running on Apache.

The page I need help with: [log in to see the link]