Check How Useful SMPS Google Customer Reviews Is to You?
Primary and the only job of the app is to help you show "Opt-in Pop-up" as mandated in the Google Customer Reviews Program.
As said above,
The app will help you get maximum reviews in relatively shorter time along with your efforts to get Google customer reviews badge on your store as well as Seller Ratings on your Google Search and Shopping Ads.
To make sure, if the app is working on your store or not, try placing a test order, check whether "Order Confirmation Page" shows opt-in Pop-up or not.
If you see Opt-in Popup is loading on your store's order confirmation pages, everything is fine from the app side.
If you see Opt-in Popup is not loading, follow this link to trouble shoot.so you can get maximum reviews in relatively shorter time.