Set up Registration Field

Geodirectory uses the same WordPress table for users, so you can use your own login/registration page.
TO change the default login page to whatever page you want, add the following to your functions.php (inside your child theme)

add_action('init' , 'geodir_redirect_to_default_login') ;
function geodir_redirect_to_default_login()
{
if(isset( $_REQUEST['geodir_signup']))
{
  wp_redirect(home_url().'/login/');
  exit();
}
}

have a look at the row

wp_redirect(home_url().'/login/');

and change /login/ to whatever is the login page you want to use