Family app sharing doesn't share already paid apps

My brother can't get the app, it says he has to pay. He is in my family on apple, and I already paid for these games, but it still says the price for him to pay. I set that purchases and subscriptions are both shared (this app is a purchase, not a subscription, but this is irrelevant). The app in question is Monument Valley 2. Why doesn't it show as purchased/free download for my brother? ps. It just came to my mind that, maybe the purchases are only shared in sense that a certain payment method is "shared". In my opinion, nothing is shared here, and in this case, only the card would be charged multiple times for each family member. If this is the case (if the "sharing" applies only to the sharing of a mean of payment, between family members), then this my question is not relevant.