SMTP Configuration

If your server don't have the SMTP configuration then this plugin can not send email for registration process completion.

Also if your user forgot their password they do require confirmation via email. So SMTP configuration is a must in your server.

See this article for configuring your email sending option with SMTP: How to Use SMTP Server to Send WordPress Emails

But if you don't have, you can do it with some third party service like mailgun or something else.

See this article for configuring your email sending option without SMTP: Mailgun SMTP Settings With WordPress