The plugin’s default configuration requires the user to provide a legitimate email address because their initial password will be sent to that address. Once they receive that, they can log in and change the password. Thus the user must already provide an actual email address that they control. This is an included feature of the plugin.
You are welcome to use the plugin with its available features for free. Also, all of the plugin’s documentation on it’s available features, including all filter and action hooks for extending it, is freely available as well – without cost or registration.
The article you referenced is not a feature included in the plugin. It is a tutorial that is part of the premium support site’s library of custom code snippets. These are tutorials that teach users how to use the plugin’s hooks to extend beyond the basic functionality included in the plugin. As such, access to this educational library is only available to support subscribers.
