How can customers pay if I create an appointment in the back-end?

If you book an appointment from the back-end, you have no means of charging your customers (since you don't have their billing information), but you can enable the "Allow payment via Payment Link" option in the Payments settings of Amelia, and then include the payment link placeholders to the message templates, so your customers can pay for the appointment through the link they receive in their notifications.

Depending on the payment gateway that you're using, there are multiple placeholders you can add:

 %payment_link_mollie%

 %payment_link_paypal%

 %payment_link_razorpay%

 %payment_link_stripe%

 %payment_link_woocommerce%

If your default status is set to “Pending” you can use the option “Update Appointment Status” which will automatically change the appointment/event status to “Approved” after the payment from the link is processed.