You can run all the commands from the terminal, or ssh into the server

See here if you need to setup SSH on the server.

Install prerequisites

sudo apt-get install mongodb mongodb-server openjdk-8-jre-headless jsvc

Download UniFi Video installer

Note the Debian package works on Ubuntu, and has been tested on the latest Ubuntu

wget https://dl.ubnt.com/firmwares/ufv/v3.8.5/unifi-video.Debian7_amd64.v3.8.5.deb

Install package

sudo dpkg -i unifi-video.Debian7_amd64.v3.8.5.deb

Login to the UniFi Video controller using your web browser and going to the following address to finish configuring the NVR.

https://your-server-address:7443