Adding Comments Support to Downloads
You can easily add support for comments on your digital products by placing a simple function into your theme’s functions.php file, or any custom plugin file.
The best way to apply the code snippet to your site is to create a new custom plugin. To do that, install the free plugin called Pluginception, https://wordpress.org/plugins/pluginception/, and use it to create a new custom plugin. Name the plugin something appropriate and then paste the provided code snippet into it and activate the plugin.