Don’t think it’s allowed. But usually every stadium has some point where you can ‘store’ things. But that’s usually a umbrella or drink bottle and such. Not sure they wanna risk taking care of a suitcase. Might be better to store it at a locker at Rotterdam central station or Den Haag.
https://www.ns.nl/en/travel-information/luggage/luggage-at-the-station.html