so what are you looking for exactly? you can enable SSH access using the dial menu on the mycroft unit itself.
otherwise you can hookup a monitor and keyboard and when you boot up a linux shell will be available with it already logged in.
for default login information please see this https://community.mycroft.ai/t/ssh-login-credentials/1698
to install screen sudo apt-get install screen.
the linux distro that jthey are using is nothing more than raspian that has some mycroft stuff added to it and that is basically just a modified debian.
can you give more specifics on what you are looking to do?
if you are looking for a GUI (desktop) you can install that too.
anyway hope this helps and if you need anything else just ask