Where do I get windows 8.1 iso?

Im trying to play GTA 5 on linux and im using Wendell's tutorial and for Virtual Machine Manager I need to get a windows 8.1 iso. Where do I get this from?

Microsoft's website, but you'll need a key, unless you find it elsewhere, and in that case I'd go windows 7

I have a windows 8.1 key but can you send me the link all I can find on microsofts website is the installer that you have to have windows to do it with.

https://www.microsoft.com/en-us/software-download/windows8

if that doesn't work you're going to have to go elsewhere

Thanks! :D

just googled "microsoft windows 8.1 download"...