my.cbs.dk is a portal created by CBS where you will be able to access a lot of practical and useful information. This ranges from advice and explanation on how to obtain a CPR, to how to ask for exam exemptions, IT Help Desk, and how to find your student number as well.
We always recommend looking at my.cbs.dk first as it has answers to almost everything university-related. If you cannot find an answer, then you should contact the Student Hub. They are always very helpful and are some of the most knowledgeable people at CBS.