If you are a member of a team or a leader who wants to understand the key concepts in Kanban, the Team Kanban Practitioner course is a great place to get started! More experienced practitioners may feel comfortable jumping straight into the Kanban System Design course. It really depends on your starting point and goals.
If you will be directly involved in designing and managing a Kanban system, you will certainly want to take the Kanban System Design course. You may still want to take the Team Kanban Practitioner course first if you feel that you are very new to Kanban and to Kanban concepts.