For anyone else who runs into this, I was able to download the package from viewtopic.php?f=14&t=1923 and install that one. I'm not sure why the other download didn't work.

I downloaded NoesisGUI-3.0.10.unitypackage just now from https://www.noesisengine.com/developers/downloads.php and Unity was unable to extract it. I'm currently on Unity 2019.4.18f1 using Windows 10 Pro. The documentation at https://www.noesisengine.com/docs/Gui.Core.Unity3DTutorial.html didn't seem...