Phoca is redirecting the user to the standard Joomla login page. They can use the social network buttons at the bottom to create an account. If they want to register an account, they can click the "Don't have an account?" link under the login form.
Again, that form is rendered by Joomla itself. JFBConnect simply adds the social login buttons to the Joomla login form. You can change the text of the "Don't have an account" link in the Joomla language files if it's not clear enough.
I hope that helps explain,
Alex
Link to register form instead of login page
