Wallet credits simplify your PlayHouse experience by letting you send tips, or unlock paid content without needing a credit/debit card transaction for each activity. As long as your wallet balance covers the cost, it will be used by default for purchases. Please note that purchases can't be split and if the cost exceeds your wallet balance, the full amount will be charged to your connected card.
Note: Subscriptions and renewals are processed using your credit/debit card, not your wallet balance.