If I click in the “Download new build” button, it opens my browser pointing to this URL. The problem is that I have not access to it, it looks like you need some privileges to access there.
The only thing “this URL” has is a message from Bob and a download URL http://www.rhino3d.com/download/rhino/wip, which is basically the same as the second one you write.
If the download is not working, that is a problem that needs to be addressed by McNeel staff.