That one works! It's downloading the tool updates properly after running the setup from your post here.
I could have sworn I tried that link before, but I bet I was still running the old itch.io setup executable by mistake. (It was 2AM after all.) The old setup is still sitting in my downloads folder alongside the new download, and windows defender didn't complain when I ran it like it does with the newer install. Doh!
Version 1.5.5 up and running now. Thanks!