To pay for an item using your credit or debit card, click the "Pay Now" button which appears when chatting with the seller for a specific item. It helps make your transaction easier and more secure but is not required in order to buy an item -- you can still pay for an item with cash when you and the seller meetup.
When "Pay Now" is clicked for the first time, you will be prompted to add your credit or debit card information into your 5miles "Wallet" found on your "Profile" page within the app. Once you've successfully entered your credit or debit card information, you will be able to pay for the item with the card provided. After you've paid for the item, please confirm within the "Order Detail" page once you've successfully received the item.