How can clients without e-mail address login with an invoice number and password printed on an invoice.

How can clients without e-mail address login with an invoice number and password printed on an invoice.

I am a physician with older patients, some of whom do not have e-mail addresses, as well as patients that have not provided us with an e-mail address. We would like to have the ability to have patients login to the payment portal using their account number and a password that has been printed on the invoice (i.e., make payments as a guest). Many healthcare payment portals give patient access this way with the option of setting up future access by creating an account with their e-mail address and password.