I've been getting into Ansible myself, what I've lreanred is that you don't neccesarily need a control node to run ansible, it can really be run from any computer, you just need to pick one and do it. You can use your personal computer, or can use a server. If you wanted to install ansible on the unraid server, I'd just run 'sudo apt install ansible' from the console.
I'd highly reccomend this video series on getting started with Ansible.