https://xibo.org.uk/manual/en/install_docker_linux.html and Xibo 1.8.0 with Docker on Ubuntu 16.04
Regarding the guide, please keep in mind that it was written when 1.8.0 CMS was released and it is also possible that docker for linux has a newer version now, as such you should be following the instructions to get the newest releases for both - as stated in the guide.
Of course the docker for linux and then docker-compose need to be installed before you install Xibo.