Thanks for the answer.
But there is still something even more confusing now than before. Is it really the responsibility of the question author to install a Jobe server? That was not clear in the documentation either. It seems to me that asking question authors to set up the CodeRunner system requires them to have access to the Moodle machine which they do not have. Typically (at least at our school) it is the system administrator who sets up the moodle and who has made CodeRunner available. The professors who are creating courses and quizzes do not have access to that installation.