?
This error is coming from nuget.exe; depending on the version of nuget.exe you're using, AD / integrated authentication simply will not work.
It's supposedly fixed in 2.8.2, but some users say it doesn't work in 2.8.3. It's pretty broken in 2.8.1 and 2.8.0. Although it sometimes works in 2.7. The 2.6's seem to be fine, for the most part.
ProGet.exe, from the now-defunct client tools, of course will work fine, or a simple HTTP PUT operation.