Dovecot failing to login Roundcube

Good afternoon. I've been attempting to get Roundcube with Postfix and Dovecot to work for a community I run. I've created an account and attempted to connect to it using both Roundcube and its installed. The Roundcube installer says it logs in fine, but Roundcubes login panel states simply, login failed.

Dovecot -n

auth_mechanisms = plain login
disable_plaintext_auth = no
first_valid_uid = 1000
mail_location = maildir:~/Maildir
mbox_write_locks = fcntl
namespace inbox {
  inbox = yes
  location =
  mailbox Drafts {
    special_use = \Drafts
  }
  mailbox Junk {
    special_use = \Junk
  }
  mailbox Sent {
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    special_use = \Sent
  }
  mailbox Trash {
    special_use = \Trash
  }
  prefix =
}
passdb {
  driver = pam
}
service auth {
  unix_listener auth-userdb {
    group = postfix
    user = postfix
  }
}
ssl_cert = </etc/pki/dovecot/certs/dovecot.pem
ssl_key = </etc/pki/dovecot/private/dovecot.pem
userdb {
  driver = passwd
}

systemctl status dovecot -l

Oct 05 18:59:22 ns3032553.ip-91-121-79.eu dovecot[30034]: master: Dovecot v2.2.10 starting up for imap, pop3, lmtp (core dumps disabled)
Oct 05 18:59:30 ns3032553.ip-91-121-79.eu dovecot[30037]: imap-login: Login: user=<holmes.k>, method=PLAIN, rip=::1, lip=::1, mpid=30045, secured, session=<QYPXpc9a4AAAAAAAAAAAAAAAAAAAAAAB>
Oct 05 18:59:30 ns3032553.ip-91-121-79.eu dovecot[30037]: imap(holmes.k): Disconnected: Logged out in=29 out=466

Thank you, I look forward to any suggestions and I can provide any other logs on request.

Solution

I enabled automatic account creation which resolved the issue. I had disabled it assuming that it would enable anyone to have an account, however what it actually means is if there is a system user with the same name and password it will generate an email account for them.