Me neither, I had to just go to the itch.io website and download it from there. It won't show up in my library like that though.
best way to add VNs to your library so you can always find them is to add them to a "collection". you can also view other peoples collections as well.
although, even though this is a good workaround, i hope the author fixes this issue soon so i can just download straight from the app
I mean, it IS in a collection, but I can't hit launch if itch doesn't think I have it installed.