Box doesnt appear in Variation

I am testing the free plugin on a page with variations now.

However, the box to enter email doesn’t appear. I think it is because to begin with, when an item is out of stock, customer can’t even choose the colour. What is a possible workaround for this?

Link: https://staging.pttoutdoor.com/shop/aonijie-sports-armband/

The page I need help with: [log in to see the link]