How do I add additional info in the checkout card?

I recently bought a template to sell my product but ran into some difficulties. I’m trying to add an additional info input in the customer info card so a customer can provide more information. However, Webflow won’t let me drag the additional info element into the card, and even if I drag it into the checkout form, the additional info does not match the template so it looks totally out of place. Do I have to contact the people who made the template or is there another solution for doing this? Let me know if I should clarify anything.

Any ideas? I’ve been trying everything to get it working but I don’t have a clue how to add it in while matching the template and in the card.