Once the customer makes the payment and passes the fraud checks, the CD Key will be made available on their CDKeys account or if you’re purchasing as a guest, through the confirmation email sent to the email account indicated in the purchase. If you had settled using ApplePay or Paypal it may have been sent to the email linked to that if no delivery email was put in during the order process.
If you had used Sofort as your payment method for your order, it may take up to 72 hours to complete as indicated during the checkout process.