Yak for WordPress

I thought I had set up the plugin to start working, but in the product page, the buy now button shows grayed out, and the tip when you mouseover says “Purchase is currently disabled, please try again later”.

What am I doing wrong?

https://gotwick.com/all-products/candles-square-pillar/

a link to the page I am working on…

https://www.ads-software.com/extend/plugins/yak-for-wordpress/