With the "No Authentication" method enabled, a user can create an account without any kind of authentication from other systems, and with no email-based confirmation that the email address that they have provided is valid, or even exists!
This is a good way to create a very insecure Moodle site, and is not recommended.
This is an option that would normally be used only for testing purposes or if your Moodle site is not available on the Internet.
The configuration page for this option only offers the ability to lock fields, enable or disable guest access, and provide an alternative login page, in the same way as other authentication plugins.
If you want to change the text that appears under "Is this your first time here?", use the Language Customization tool to edit the language string 'loginstepsnone' found in moodle.php. Note, this string is different from 'loginsteps', which is the string used for Email-based Self-registration. Text added in the Instructions box found in Site administration ... Plugins ... Authentication ... Manage authentication is not displayed when No Authentication is used; you must edit the language string to make changes.