Click the Payments settings tab.
Do the following:
1. Specify the amount of the advance payment.
2. Check the Accept other payment types checkbox.
3. If necessary, specify the payment instruction.
It is displayed in the order cart.
4. Set the Auto-confirmation of orders paid using other payment types.
Specify the message on the screen after the order is made.
Then, customer orders will be confirmed automatically.
Otherwise, they will be in the Pending status.
5. Enter the Website address.
It will be opened in the iframe immediately after the completion of the order.
Here the customer will make a payment.
6. Specify a suitable width and height.
7. Save it.
Check the result.
There is a payment instruction in the customer's cart.
And after the order was completed, the specified page appeared in the frame.