You can link the Zone with the appropriate Banner from the Advertiser in the revive Adserver under Default manager.
--> Login as the Admin, switch to Default manager.
--> Click on Inventory.
--> Click on zones
--> In the zone list section, beside the name, you can see "Linked banners".
--> Click on Linked banner link and you will have the option to select the banner for the zone.
--> select "Link Individual banners" or "Link Banners by parent campaign".
--> Select the advertiser to link. The Advertiser who has the banners of the matching size will be listed.
you can link the appropriate banners in the section.
Hope so you got the details. If you need any further details, provide more information about your requirement.
