How to activate Apple Card on iPad?

Are you trying to activate the physical card for use (follow the info in the link at the top of this page) or are you trying to add the Apple Card for use when using your iPad? https://support.apple.com/guide/ipad/use-apple-card-ipadca55f179/ipados

You can’t. You need to do it with an iPhone. The instructions will be with the card. At least that’s my understanding