No highlight, no file tree, no php lookup

I was expecting more of this plugin. It doesn’t seem to work as advertised.

I see the files from the current child theme but I can’t navigate to subfolders and there is no code highlighting.

When looking up php functions I get a 404 (page not found). Example:
https://developer.www.ads-software.com/reference/functions/bbp_get_forum_title/

I hope the plugin will improve in the future.