This plugin hasnt been tested with the latest 3 major releases of WordPress. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.
This sort of works, but it hijacks some URLs. I tried to create a "signup" page with an appropriate slug/permalink: www.example.com/signup and it absolutely didn't work, and redirected back to homepage. Same with "register." There is no reason for this, and no options. Look instead at "WP User Manager" and "Clean Login" for much better plugins.