Review pops would pull the Google My Business Link automatically when you set up the business, so you could immediately collect reviews and display them on the websites.
However, if it's a brand new Google My Business account or it has some incorrect information and it couldn't be pulled from the automatic setup, you might see the notification like this:
You can easily add the link manually following these steps:
Step 1. Look up the Business on Google Search
Step 2. Click on the maps and grab the link from the browser address bar
Step 3. Then navigate to the tool called Pleper following this link: https://pleper.com/index.php?do=tools&sdo=cid_converter
Step 4. Enter the link from the Google Maps into the converter then click the "Convert and Generate" button
Step 5. Scroll down and find the CID link on the bottom of the page, then copy
Step 6. Navigate to Business - > Set up tab and paste the Google CID link into the Directory monitoring field
Make sure the Monitoring toggle is set to "ON" position.
Step 7. Then click the Save button.