The destination ad set has no linked Facebook Page. An ad needs a Page to be created, and the system couldn't find one because the ad set has no active ad with a linked Page.

How to fix it:

  1. In Meta Ads Manager, make sure the ad set has at least one active ad with a linked Facebook Page.
  2. Reprocess the ad in Ads Editor.

If it still fails, check that you have the Advertiser role on the Page.