I'm trying to see if Trello is right for our team before we commit to purchasing. We have about 12 people on our board under the free account. Unfortunately, our users are now getting an error saying we've reached the limit for power up users on our board. I can't find anything detailing how many users on a board can use the power ups only that we can use only one power up under the free account. Any ideas how everyone can get the power up? Or do we have to purchase the higher to make this work?