Plugin virtualmin-dav, Plugin virtualmin-mailman missing

Hello again,

I'm migrating some websites from a CentOS 7 system to an Ubuntu 16.04 server. Two of the sites migrated brought down Apache upon restart:

Oct 14 11:38:31 osepweb2 apache2[21675]: AH00526: Syntax error on line 55 of /etc/apache2/sites-enabled/more.northwestern.edu.conf: Oct 14 11:38:31 osepweb2 apache2[21675]: Unknown DAV provider: filesystem Oct 14 11:38:31 osepweb2 apache2[21675]: Action 'configtest' failed. Oct 14 11:38:31 osepweb2 apache2[21675]: The Apache error log may have more information. Oct 14 11:38:31 osepweb2 systemd[1]: apache2.service: Control process exited, code=exited status=1 Oct 14 11:38:31 osepweb2 systemd[1]: Failed to start LSB: Apache2 web server.

Oct 14 11:40:51 osepweb2 apache2[22256]: AH00526: Syntax error on line 55 of /etc/apache2/sites-enabled/steam.northwestern.edu.conf: Oct 14 11:40:51 osepweb2 apache2[22256]: Unknown DAV provider: filesystem Oct 14 11:40:51 osepweb2 apache2[22256]: Action 'configtest' failed. Oct 14 11:40:51 osepweb2 apache2[22256]: The Apache error log may have more information. Oct 14 11:40:51 osepweb2 systemd[1]: apache2.service: Control process exited, code=exited status=1 Oct 14 11:40:51 osepweb2 systemd[1]: Failed to start LSB: Apache2 web server.

When I went back and inspected the process to import the sites, I noticed the following message:

Warning - the following features were enabled in one or more of the domains in the backup, but are not enabled on this system : Plugin virtualmin-dav, Plugin virtualmin-mailman How do I get these modules installed?

Thanks!

Ryan