Error 1033 and my truenas

I am new to all this. I got a truenas system that I am pulling apps and was able to get to my system by making a sub domain and pull up diffusion, and pull up my truenas itself. However, when I go to my top level domain I get Error 1033. I figured that is not pointing to any website and my question is how do I point the top level domain that I got from clourflare to a specific port on my truenas that is not using port 80. when I try to go to add my top level to go to my startup page on truenas it says the domain already has a dns record. I’m a bit reluctant to delete the dns record because it may break everything else.