(if you can't see this message properly, please click on this link: https://commentshelp.freshdesk.com/solution/articles/6000131061-how-do-i-add-comments-to-my-wix-ecommerce-store-)
In order to set up up of the comment box to show in each of your Shop's product page, please try the following:
1. In the Wix editor, click on the "My Store" button on the left side of the screen, then click on "Store Pages" and select the "Product Page" option:
You can read more about the Product Page in the Wix Help Center.
2. Open the Wix app market, and add the Comments application to your "Product Page" page:
3. After adding the Comments app into your "Product Page" page, drag it to the desired location in the page. Double click on the app to complete the setup, and then publish your site to apply the changes.