The Moodle CodeRunner question type plugin requires a Jobe server on which to run student-submitted jobs. JobeInABox is a container image that provides a basic Jobe server that runs all the standard languages but does not have a mysql server installed so cannot use API-key access. For normal use, that's not a problem - API-key access is relevant only to Jobe servers delivering services to multiple clients.
NOTE: for security and performance reasons it is strongly recommended to run Jobe on a dedicated standalone server, even when running it in a container.