DSF Symphonic Strings HD installation fails

I recently upgraded to Sonar X2 and got the free DSF Symphonic Strings HD download with it.  I downloaded the ZIP from my account page and extracted everything.  The first problem I encountered with the installer was that it won't let me select a hard drive to install to, but I decided to just free up enough space on my C drive and try to fix it later with registry settings and whatnot.  However, when I do the install now, it zips through it in less than a second and claims that it's complete.  But I'm pretty sure it didn't actually do anything.  I can't find the files installed anywhere and I can't find the instrument in Sonar.  (And none of my hard drives have lost a few gigs either...)

There does seem to be a filename that briefly flashes by, as if something is being installed, but it's so quick I can't even read it.

The only odd thing that I can remember doing was, before I freed up enough space on my C drive, I once clicked through the disk space warning anyway just to see what would happen (I thought maybe it would allow me to choose a drive afterward).  And then it did the thing where it appeared to install very briefly.  But even after freeing up space it does the same thing.  Is it possible that I tricked it into thinking it installed, so now it won't try to do it again?

This is on Windows 8 Release Preview, which I realize is probably not officially supported, but I was hoping someone might be able to figure something out.