Dear, i have check your site i see short code is working in your site (see attachment), you can use this short code to build a page template for single product you can see video example in HERE
Dear, i have check plugin with ‘X’ theme. to fix your problem, you need create custom default template of plugin. please download and extract file ‘archive-product.zip’ then download file ‘archive-product.php’ and paste to folder ‘{yourtheme}/dhvc-woocommerce/’ (create folder ‘dhvc-woocommerce’ if not exits).
Dear, if your theme support text link Prev and Next product in single product, the plugin will work with it, but if your theme not support it, the plugin can not create the text link Prev and Next product in single product.
