ricks1950
I installed the package following the write up in the wiki, and the expected things did not happen. The service starts, but there is no panel in the admin interface, and the cgi-bin web pages to manage group membership do not work.
Well I justed installed the mailman contrib as per wiki article onto a lightly modified SME 7.5.1 (fully updated), and it installs OK for me. I can access the management interface & see a panel in server manager.
So the possibilities are that you have a heavily modified server which has something installed that is incompatible with mailman, or you are using SME8betaX (and not 7.5.1 as this is a SME7.x forum), or maybe the download files were corrupted as you did the yum install.
I made no system changes etc, just installed using yum, did the post-upgrade & reboot, then was able to access the management web page.
This is the first time I used mailman, so it seems to have installed OK, and I was able to subscribe to the list and send and receive email messages, so it appears to be working.
Perhaps you should setup a test server (7.5.1 fully updated) and try installing it, and go from there.
It works for me, so there is something not right at your end.
I would stop trying to do on SME server whatever you did on Ubuntu (to get mailman working), as it is not necessary and is only misleading you.