How to Activate Review Pop-ups in your Shopify store
First, in Shopify panel go to Online stores, and then choose Themes. In current theme find Actions and Edit code.
Check your Layout/theme.liquid file. You should have this code in the bottom of the page
If you don’t see it insert the code.
Follow next steps to install pop-ups: Also in Layout/theme.liquid file put this code above the previous one
Then, go to General settings and check if your Review Widget is activated.