No you do not have to add a credit card to the app in order to use. Unlike other companies, we take all forms of payment and you do not have to enter it into the app. During the initial setup, you can skip entering a credit card and it will default your payment method to cash. If you do have a card saved, you can swich back and forth in the order preview screen on your payment method.
Also if you choose your credit card as payment, you can always swipe a different card, or pay in cash at the completion of the trip. Just let the driver know and he can remove the saved card from his order.