I tried to install it on Windows 8 on my desktop (not 8.1) and was informed that it is only for Windows 7 SP1. I could help but roll my eyes.
They are really strange: if I had Windows 7 I'd be able to install IE 11, but since I have Windows 8, I'll have to wait until October 18 and then I'll have to install the whole Windows 8.1.