The IAB category assigned to your creative can be found by clicking on the creative name to open the creative details window. This field is displayed below the creative in the ‘Creative Category’ field:

These categories come from the Open RTB Specs, that can be found here in table 5.1 ‘Content Categories’: Open RTB Specs v2.5

If you believe your creative has been assigned an incorrect IAB category, please submit a ticket through the Help Center. Be sure to include the Advertiser Name and ID associated with the creative in question so we can assist you promptly.