When trying to use Tap to Pay on iPhone an iOS alert displays “Unable to Set Up Tap to Pay on iPhone - Remove one or more cards from Wallet and try again.” What does this mean?

This error occurs during setup on a new device if there is insufficient space to load Tap to Pay on iPhone. Insufficient space can be caused by having too many payment cards setup in Apple Wallet. Try removing one or more cards from Apple Wallet and then try to use Tap to Pay on iPhone again.