Previewing your graphics and ad sets can be done following the steps below.
Click Matches in the left hand side dashboard
Click the arrow situated to the left of the respective match, a drop down will appear
Hit the ellipsis next to the corresponding match that you wish to preview graphics and ads for and then select Settings under the Overlay section
Select the template that you would like to preview and also the relevant ad set. In the below example, the Intro graphic is selected with a Large ad displayed
In the next example, the MatchID graphic is selected with a Long ad displayed
To utilize customizable ad sets, users must be using a Graphics + Brands tier for their productions.