I'm here to help you issue a receipt once payment is made by your customers, emily31.
For now, you'll have to manually send an email to your customer confirming the payment. To do this, you can follow the steps below.
For future reference, you can also read this article: How To Email Or Print An Invoice.
Please touch base with us if you have any other questions about invoices. We're always right here to help you if you need further assistance.