When clicking the "New App" button, the dialog that opens "Finding apps for you to use. Please Wait." fails to load anything and simply spins and nothing happens. I attempted to login with our AGOL org account as well as not signed in and get the same result.
I was trying to run this on a Windows Server 2008 R2 box that is a designated "developer" environment for us.
FYI: I ended up installing AppStudio on a local computer to test it out (Windows7 machine). However, our org is rapidly moving to Virtual Desktop environments, I will have to coordinate to get it installed there.