[Dovecot] userdb section not recognized in dovecot.conf. Help?

[CypherPunk]

I'm following a tutorial[1] on how to configure dovecot and the tutorial
says to insert the following configuration options into the dovecot.conf
file:

 disable_plaintext_auth = no
 mail_privileged_group = mail
 mail_location = mbox:~/mail:INBOX=/var/mail/%u
 userdb {
   driver = passwd
 }

This seems to have worked for a lot of others using this tutorial but
not for me. When I try to start dovecot, I am told that the section at
userdb is an unknown section type.

I've spent the last few hours on Google searching this out and I've
gotten conflicting answers that don't make sense. Is this the proper way
to use the userdb directive?

For information, I've also tried

userdb{
	driver = passwd-file
}

and that didn't work either. So I'm assuming that perhaps userdb is
deprecated somehow but I don't know what to replace it with. Can someone
point me in the right direction?

Many Thanks!
CypherPunk

[1]
https://www.digitalocean.com/community/articles/how-to-set-up-a-postfix-e-mail-server-with-dovecot