PayPal integration for a workshop registration, but also allow registration with no payment?

How can I use PayPal integration for a workshop registration, but also allow a method that people can register for the workshop, but not pay in advance (because they will pay when they are at the workshop)?

The following guide describes the exact setup you are looking for:

https://www.jotform.com/help/120-How-to-Set-up-Paypal-Along-with-Other-Payment-Options

Except instead of labeling the options as "Check" you would label them as "Pay at the workshop" or something similar.