AppStore
why Can’t I download free apps on AppStore without paying?
iPhone X, iOS 14
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Top-ranking reply
Are you actually seeing a charge for a free app? Or are you questioning why you have to have a credit card on file in order to download apps? If your question is the second, the reasoning is this - many free apps are only free for a limited time, then there is a charge. Also, many free apps have purchasing abilities within the app so Apple’s policy is that you must have a credit card on file if you want to download apps.
You can read the Apple Recommended answer in this discussion:
Why do I need a credit card to download a… - Apple Community