• Read it carefully: it usually states that you can take the Kenntnisprüfung (KP) to prove your knowledge, and which subjects are covered.
• Register for the KP with the responsible Prüfungsamt/Ärztekammer as soon as you can, since waiting lists exist.
• Make sure your language requirement (FSP) is on track in parallel.
• Some Bundesländer also allow an Anpassungslehrgang (adaptation period) instead of the KP — check if your Bescheid mentions an option.
So the practical next step is almost always: secure a KP date and start structured exam prep. The Bescheid is your roadmap — follow exactly what it lists.