Consider how a client pays an order in the CRM Store.
A sales manager sends an SMS message to the client.
The client follows the link and checks the information about his/her order. Then he/she selects a suitable payment method (in our case, it's PayPal) and taps Pay.
The client gets redirected to his/her PayPal account page. There he/she needs to confirm and complete the payment. The receipt will be sent to the client's email address.