Generally you use the name of the bank that underlies the prepaid card. There are too many different types of cards to know in a user forum what the underlying bank is for each one. You'll need to do that homework.
Try an Internet search on the routing number and see what bank comes up for that routing number. That may give you a clue. Does it show Metabank?
Or if you can't tell that way, or if you can't tell from the FAQs or info in your online card account, the safest thing to do is phone their customer service and ask what bank name to show.
