The Samsung Book Keyboard Cover was only available for pre-order, i.e. if purchased before the release date.
If you bought it during this period, you have to open the "Samsung Members" application on the tablet itself, create a Samsung account and then have a promotion tile via which you can register the tablet for the promotion (enter serial number, upload proof of purchase, register shipping address).
If all the data is correct, the Book Keyboard Cover should then be sent directly from Samsung. Digitec itself has nothing to do with the promotion, which is why it was not supplied directly.
All details can be found here:
https://images.samsung.com/is...