Club Challenge is a type of recurring event that takes place on weekdays between two Tournaments. The aim is to fill up the specified number of catering boxes together with your club members. By filling the boxes together, all of the members in your club gets to receive up to three reward boxes together!
Contribution is not mandatory however, the more you contribute, the more catering boxes are filled, the faster the tiers are completed and rewards are won. Being present in the club while a tier is being completed is mandatory though. You will not receive the rewards that were unlocked before you joined the club.