Not really sure if this was intentional or not (and the page is just outdated), but I was following the installation instructions on the page, I'm using Media wiki 1.35 so I downloaded that version of this extension first. Running my wiki threw me an error telling me that the BlueSpiceFoundation.php file was missing (which it was). So I downloaded both the master and 1.31 versions and the 1.31 version had the BlueSpiceFoundation.php file . . . I copied it to the BlueSpiceFoundation folder in my wiki extensions folder and it worked after that.
