Plugin Help BuyRegion Help

Hello! My name is Bert and I really need your help. I have the BuyRegion and WorldGuard plugins. Both work fine to an extend. So, I created regions and what not and made it so players could rent and buy them but when they do, they still cannot build inside them. Anyone who is opped can build just fine but players who buy or rent the regions cannot build which is a problem because it defeats the whole point in selling or renting a region. Can you please help me figure out why? Players can buy/rent shops without a problem. But when they try to build or edit anything inside the region they now own, it will not let them. Like, is there a certain permission I have to give players to be able to edit their regions or something? I really need your help. I need to fix this issue before tomorrow ends. Thank you!