How might I use $_SERVER[‘REMOTE_USER’] in the context of OpenAM Single SIgn on to allow users to authenticate?

I stumbled upon this module called OpenAM Authentication that I’m going to experiment with on a development server. Merely reading the plugin’s FAQ page has me very hopeful

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)