I have variable products. Can you please check and let me know how can I make th

Hi Support,
I am using your paid plugin WooCommerce Checkout Upsell Funnel Premium. But it’s not working properly on my checkout page.
This is my site link: https://jewelryfactory.co.il/
I have variable products. Can you please check and let me know how can I make this plugin work for my site?
Or is this plugin compatible for variable products?

Here I am attaching the video which shows how I am not able to select option for variable products on checkout. It’s working fine for normal products. But I have variable products so I want to make it work for variable products as well.
https://www.awesomescreenshot.com/video/23726751?key=1f43071169835b6b5c25fef31acf676d

Please check and advise.
Waiting for your reply.