I’m not an Istaria player, but I did recently have the pleasure of assisting someone to set it up based on an old guide on the Istaria site.
As a long time Unix, and Linux admin… I found the guide a little overly complex for newer users, and in some places inaccurate enough to need clarification….
So, the following is my summary of how best to do the installation, with a current version of Ubuntu (Based on 23.04, so should be valid for 24.04+).