From the description, it sounds like they got that opposition research doc that every other media organization had and which most of them said they didn't publish because they weren't able to validate it.
> "it’s a variety of documents from different types of institutions that are associated with the election campaign, some quite unexpected angles, some quite interesting, some even entertaining"
The fact that it was 'associated with the election campaign' and 'entertaining' made me feel it was there. I don't remember seeing other docs that satisfied both criteria, but it is only a guess and I could be wrong.