Answer:
Greg can see previews of his ad in the Preview tab of his Google My Business account.
Google My Business is a free tool for businesses to manage their online existence across Google including Search and Maps. It also provides them to edit their business information which helps customers to find their business. They can also find how many customers searched for their business.
So once Greg's ad has been officially accepted, he can enter the specific keywords he’s targeting to have a generic view of the ad in the browser. Google gives examples of desktop ads using the keywords selected in the campaign to make a general preview. As Greg types his URL, headline, and description, a generic preview of mobile and desktop versions of his ad will show up.