you have to open hugo.zip, or click on the view contents link beside it

Yes, I did that. I see in there the vinge novel but NOT the version with annotations.

The annotations are there in the RTF files, but there is something quirky about the format of those RTF files - perhaps they predate standardization or something. If you open one of the RTFs in a straight text editor like emacs or vi, you'll see them. There was a bit of discussion around this here, a few years ago, when this version was re-released [1]

[1] https://news.ycombinator.com/item?id=24876236

Oh wow thanks!