After completing the checkout, the customer is directed to the success page. There, a button labeled Add to my calendar appears next to each appointment.
By clicking this button, the customer can choose to add the appointment to their preferred calendar, such as Google, Outlook, iCal, or Yahoo.
Note:
If your offer requires manual confirmation, you need to confirm the booking after accepting it. The customer will then receive a confirmation email with the option to add the appointment to their calendar.