Why do I need to provide credit card data to download a free app on iPad?

Hi! I received an email that somebody used my ID to download an app in Asia ( I live in Europe) and changed my password for the AppStore. This happened just after I bought my iPad. Now when I want to download a free app on iPad, the AppStore asks me for the confirmation of my credit card data ( never halpened before and is not the case on my iPhone) - do I need to provide this data or has my iPad been hacked? Thanks for any support!