If you already have a CASUS learner or authoring account, you can go to http://player.casus.net and login with your credentials.
At many universities CASUS is connected to the faculty learning systems, such as moodle or blackboard. Thus, no registration in Casus is necessary and you can access the cases and courses directly from your faculty environment. More information can be provided by the teachers at your institution.
Some projects allow free access to examplary cases (guest access) or complete courses: