User authentication with Apache .htaccess and form-based login are two different, unrelated techniques, though you can use the .htpasswd content as database for your form-based authentication. Of course, you can still use .htaccess to restrict access based on IP addresses or host/domain names, before even reaching the login form. I guess that's what the site you are referring to means about Works with - and dramatically enhances - your server's basic htaccess protection.

If you use the .htaccess to authenticate users by enabling the require valid-user directive as well as providing login form, then the users need to authenticate twice.