If you have a subscription in trustindex.io, you can forget the plugins’ “Free Widget Configurator” tab.

Why? In Trustindex, your new reviews will show up automatically, so you should use the contents of that account.

How? There are many ways:

After you have saved a widget in admin.trustindex.io, you will find the WordPress shortcode, what you can copy into your WordPress page/post. Detailed help here: https://www.trustindex.io/how-to-insert-your-widgets-code-into-your-site/
You can connect your Trustindex account with the plugin: just log in under the “Log in” tab. After it, you can embed your widgets, generated in Trustindex account, with a simple click: When you are editing your page or post:
1. just insert a new content block and search for “Trustindex”:
2. after it, you will find your generated widgets in the select box of the Trustindex block. Select one of them and it will appear in your page/post. Also, you can insert any widget by its ID: