I’m sorry that you ran into issues here. The require registration setting is under Directory Admin->Manage Options, Registration tab. Turning it off would allow anyone to post listings without registering on your site.
I’m not sure what problem you had with that setting–if you are having trouble with the 3.2.3 version, we have another version you can try that we’re about to release, pending testing. Contact me to get it: http://businessdirectoryplugin.com/contact/
We’ve not had reports that this setting failed to work otherwise.