Free download requires billing account, why?

The system still has to have something to "charge" even if it is a free item.

It's a quirk of the billing system. If you create a PayPal account (can be empty, no need to add money to it) and tie it to your Microsoft Account that will be enough to fulfil the 'payment method' requirements. Then you could download your free items.

I found out just now you can get certain content on the Store on Xbox One, like the Dog Breed one. It's free. So that's great!

The only thing is, I don't understand is, why when I am claiming free content, does it ask for me to change payment options and my billing address???

It even says:

"Free

This purchase channel requires a billing account. Please add a valid payment instrument. You will not be charged for a free item."

Well, if I am not charged for a free item, why do I need to fill in my billing address and payment information?

The 360 store is set up differently than the store on the One/website. The One/website does not consider your Microsoft account balance to be a valid payment option for 360 content so you have to have either a credit card or Paypal on file in order to make
360 purchases, even if they are free.

DarkMoofey, i click it but it is asking for Billing...

But its showing FREE!

GUYS I DONT WANNA BUY, I WANT TO DOWNLOAD!

AND I WANNA DOWNLOAD IN MY PC!!!

It is showing its FREE then why it is asking for billing???