How can I do free download without putting in my card information

Create or use your Apple ID without a payment method - https://support.apple.com/HT204034

If that doesn't work then you will have to enter a card, if only temporarily. There can be various reasons why a card is required. For example, if an app has a trial that automatically rolls over to a subscription.

Even if the app you desire says, "Get" instead of showing a purchase price, you still have to "buy" it from the store. Just tap on the "Get" button and confirm the "purchase" with your finger, face or password, as appropriate. You will get your download without having to register a payment form.