Help with Domain Mapping to dedicated IP

Hello, I have a dedicated IP 174.120.129.105 for my domain myfitbodybiz.com. I am trying to get Domain Mapping to work but if you go to the IP address it goes to an empty directory. My host is HostGator and they are telling me that I need to input the custom domain for each user manually in my cPanel. Shouldn’t a new user simply be able to add an “A record” for their domain, and then use your Domain Mapping plugin to setup the rest? Without any input from me?

Thanks

Chris