1. Navigate to the Online Store section of your Shopify store, and under the Themes page, look for your preferred Shopify 2.0 theme and click Customize: 

2. Click on Theme Settings in the bottom left corner of the Theme Customization page. 

3. Click on App embeds tab on the right side of the page under the Theme settings block, enable the Product Reviews App, and Save the settings.

4. In the App’s Settings section, navigate to Layout Settings, click on Enable button, and Save.