You can find the instructions on the manufacturer's page a little further down. There you can see which parts of the series it is compatible with.

With the following yes:
rollyJunior
rollyFarmtrac
rollyFarmtrac Classic
rollyFarmtrac Premium
rollyX-Trac
rollyTruck (Unimog)

But not with:
Rolly three-wheel tractors
rollyMinitrac
rollyKid

Unfortunately, the Cat dumper probably belongs to the rollyKid range, so it would not be compatible.

FYI for all. I ordered the trailer and tried it out on the aforementioned children's dumper. Fits like a glove (height of drawbar, hole for locking pin etc.) .... Sits, fits, wobbles and has air :)

ok. Thank you for your help. Thank you very much.