It is possible to set up Review pops for businesses that don't have a Google my business listing, have no reviews on Google, or have bad reviews.  Once you set up the business in Review Pops, you will be able to add the reviews you want to display on the review pop manually. 

Step 1: Navigate to the Business

Step 2:  Navigate to the Review Inbox and Add a Review 

Step 3: Add a review manually