Currently we do not have jReview app, are you referring this 3rd party app? https://stackideas.com/apps/item/3384-jreviews-directory-reviews

If yes, I think it required you to install this jReview extension first in order to work correctly. https://www.jreviews.com/joomla

Before you install anything, you have to consult with jReview developer/support from them first.