I was able to find the document:
https://7f215854-ce29-4a12-9bb0-f4e7eb88d38a.filesusr.com/ugd/aa4aac_e69847bdf5814f43b69d49e2962a17d8.pdf

It comprises five DIA reports. from 2009 and 2010 on advanced materials, but contrary to this article there is no mention whatsoever of the source of these materials being from UAP. It’s odd that they provided this response to the FOI request, because it seems not to address the request’s intent. Maybe they didn’t understand that intent! In any case the notion that they admitted to crash retrievals is completely fanciful.