[Plugin: PHPBB Single Sign On] Different Auth Mode Error

Well, it’s somewhat the same. I have phpbb set up in a separate database from wordpress. I did all the options manually, and in the options page I still get an error for the Auth Mode setting–and nothing else.

My setup is like this:
https://site/forums/
https://site/wordpress/

I checked my apache logs, and this is the strangest part. The error I’m getting is: https://site/index.php “not found or unable to stat”

Originally my site used a .html homepage, but that was no biggee. I flipped the filetype to .php. It didn’t help. What is going on?

edit: forgot to mention I did manually change the phpbb side via the ACP