Payment/ Not being able to download any apps.

So i had this game called clash royale. I deleted and wanted to download it back again. When i went to the app store and clicked the re download button it took me to a page that said verification required, when i typed in my password it took me to a page where i had to fill out a payment form for a free game. I put in my details and it says it doesnt work. WHAT DO I DO?