QR codes are a way to direct members or future members to a link. This might be for a store purchase or to sign-up for a membership.
You can put QR codes on a flyer to direct prospective customers to sign-up for a trial. You can also put QR codes for products in your store to have easy payment access.
For memberships, under the 'Membership Set-Up', click the '$' for the payment plan. Then, click the 'QR/URL Link' option.
For store products, under 'Store Set-up', click the 'Purchase Link' of what product you want to display.
Best practice is to screenshot the QR code to paste into a document or print it. Be sure to get the whole QR code in your screenshot.