Can't use Apple ID balance to buy app

I tried to buy an app to use up my credits in Apple ID. There are 10 Euros.

I got into this page asking me which method I want to use to pay.

I picked Apple ID.

Then I got to this page.

two options showed up: redeem and add fund. No option to use the balance to pay. I don't want to redeem nor add fund.

Not really sure where I should tap to make payment.

the redeem page is like this:

I don't need to redeem as I want to use my balance 10 Euros.

Any suggestions?