Why is my phone asking for my card info for a free app?

Here is how to create or configure an Apple ID with no payment method:

Create or use an Apple ID without a payment method - Apple Support

If you can't remove your last payment method or use no payment method with your Apple ID - Apple Support

Apple does indicate that In some cases, like if you're using an existing Apple ID with the App Store for the first time, you must provide payment information. (This was mentioned in the previous reply.)

You must have a valid payment method registered in the App Store to download content. It doesn’t matter whether the apps are free or not.

Axel F.