You can sign up to the Retail Partner Portal by logging in with the Facebook account which is associated with your Facebook Business Page.
Before signing up, please ensure that you’re the admin of the Facebook Business Page so that you can grant all necessary Facebook Advertising permissions for you to take full advantage of the Free Sponsored Social Media Ads for your business.
How do I access the Retail Partner Portal?
How do I add a social media account to my review section?
To add for example your Google My Business Page, and include Google reviews in the review analysis section of the Portal, click the “+” symbol on the Google button and enter your Google account details when prompted.