Addendum:
I have again looked at various reviews and thereby gained the impression that some do not read the documents lying in the package or simply are too stupid.
There the URL to verify the eligibility (student / student ID, etc.) is clearly indicated. The enclosed serial number is not required later when you install CS6 (which will be sent via email) but a provisional, the (eg student ID) is required when submitting the documents. Quite simple really.
1. It sends its data + copy of the student Stdentenausweises.
2. You get sent to a serial or license number.
3. To ensure that you installed CS6.