MailServer, Postfix, lack of user and fail at authtest

[Erickira]

When following the https://wiki.gentoo.org/wiki/Complete_Virtual_Mail_Server I fail at the "Courier-IMAP to Database".

First I do not understand at whichpoint this "testuser" was created or affected to the system.
When I try to test it I get a: "Authentication FAILED: Operation not permitted"
When I try the command "SELECT * FROM mailbox;postconf -e 'home_mailbox = Maildir/" (seen the log message about checking this table for the user and returning nothing)
I notice that there is not user at all, the table is empty.

How do I create them?

Thank you in advance for any help you can provide.
_________________
New gentoo user. Please take care of me.

[Syl20]

If you followed the whole tutorial, you have postfixadmin configured and running. You can use it to create virtual users : https://wiki.gentoo.org/wiki/Complete_Virtual_Mail_Server/Postfix_to_Database#Querying

[Erickira]