This feature is relevant if you want to export creatives to a csv file.
You will find the "Export"-button next to the filters on the main bar in the Creatives Manager. Every creative matched by the filters will be exported no matter how deep they are located inside the creative sets.
After you click on the button a notification will be redirected to the export overview.
The following screenshot shows you the export overview. The export overview shows you a historical list of all exports that were done for this advertiser. Here you can simply click on Download to receive the CSV file with your exported creatives. Just as with the Overview page you can select a single export to view additional information in the Info Panel.