Yes, Virtualmin Professional should have configured Dovecot appropriately for receiving mail via POP and IMAP, and open the firewall ports needed for those services.
What’s in the /var/log/maillog (or /var/log/mail.log on Debian/Ubuntu) when you attempt to retrieve mail?
I ended up re-imaging my server and went through the install again.
all is working now.
I also had to allow dovecot to allow plaintext authentication in non-SSL mode.