This video shows you how to install the UniFi controller on Ubuntu. I am using an Ubuntu Desktop version but it is better to install it on Ubuntu Server, you can do the same process on Ubuntu Server just us SSH to get in there instead of the Terminal through the GUI.
I have used the Easy Install Script for installing the UniFi controller. That is available here: https://community.ui.com/questions/Un...
This script works quite well, just install the pre-requisites and then run the script and you will have a UniFi controller running.
You can also download Ubuntu Server from here: https://ubuntu.com/download/server
If you want to have a cloud based UniFi controller you can easily spin up an Ubuntu Server instance on Azure and install the UniFi controller on the Azure Hosted Ubuntu server.
If you have any questions please leave them below.