To meet the customer's requirements for an ad placement of a vertical banner with specific size and content attributes, the fields that need to be configured in theAd Creative Size Typeobject areWidth and Height. These fields allow for the specification of the banner's dimensions (120x600), which is crucial for ensuring that the ad creative conforms to the required size for effective display. The position (left or right) and content type (animatedGIF) would typically be managed within the ad serving platform or specified in additional fields or instructions associated with the ad creative but are not standard fields in the Ad Creative Size Type object.