Clubs must have entered the event as a Majors club to qualify for rewards given to Majors. So you will stiil see the Minors rewards for the event just completed. However from now on, your team - being in the Majors - will start to receive Majors's rewards going forward.
If you did not receive the club rewards at all, try completely force-closing and reopening the app; this may help prompt the reward screen.
If your club leveled up multiple times while you were not online, you will only get the most recent level up rewards.