Hey there! 😀 Users will need credentials for your specific site in order to login. Go to ‘Settings->General’ in the WordPress dashboard, and you’ll see this option: http://grab.by/x0oE. If that’s checked, then a ‘Register’ link will display on the Community login page (screenshot), in order for users to get a login for your site.
Does that help to answer your questions? If not, just let me know how I can help further. Thanks! 🙂