When processing a payment at check out, staff will be required to input the 3 digit security code on the back (or front on AMEX) cards if taking payment manually.
If using a zingfit compatible card reader, the staff might not be required to input the code. This depends on the payment gateway (Authorize.net, Stripe, etc) settings.
Simply log into your payment gateway account and edit your settings to require or not require the CVV code.