"The ProFTPd server does not appear to be installed on your system, or has not yet been set up properly in Webmin's ProFTPd Server module. If your system does not use ProFTPd, it should be disabled in Virtualmin's module configuration page.
… your system is not ready for use by Virtualmin."
The above message is what I see when I log in to Virtualmin. It looks like ProFTP IS installed, but I’m not exactly sure what to do to configure it so that Virtualmin is happy.