Does the app work with variants/options?

Yes the app works with variants (color, size etc). You can check out our demo store that shows the registration form working with variants.

Go to Demo store

If your store is using the older blueprint themes, some of them use an image as the add to cart "button". This can cause the script to not recognize the out of stock status properly. There is an adjustment we can make to adjust the script for the theme. Simply create a support ticket and include a link to an out of stock product so we can make the adjustment.