Thanks for the tip, the price is now back to the usual level.

My whiteboard is 100x200 cm and hangs perfectly. How much weight does your whiteboard have? It can't be that heavy 🤔

According to the manufacturer, the brackets are compatible with " CC and SP boards." Source: https://magnetoplan.holtzofficesupport.com/ersatzteile/schreibtafel-zubehoer/aufhaengung-fuer-whiteboards-sp

Unfortunately, the manufacturer has no assembly instructions on its homepage. I assume that since there are only 4 screws including brackets, no instructions were probably provided. Source: https://magnetoplan.holtzofficesupport.com/ersatzteile/schreibtafel-zubehoer/aufhaengung-fuer-whiteboards-sp