Buttons rather than Dropdowns for Variants

Based on the “Admin Response” in this post,Buttons as variant selectors | Webflow Wishlist it sounds like this is now possible.

However if i watch the video here, Add to cart | Webflow University I cannot see the “Variant Selector” option of “Buttons”

What have I missed?

Here is my site Read-Only: LINK
(how to share your site Read-Only link)