Emirates Skywards

Emirates Skywards and spending Miles

Why am I asked for a credit card number when buying a flight reward with my Skywards Miles?

Credit card information is required to cover the government taxes and airport charges levied on all ticket purchases, including those purchased with Skywards Miles, whether with Emirates or with a partner airline. Airport taxes are compulsory and are not charged by the airline; rather, they are usually charged by governments or airport management companies.