Microsoft windows mobile app development system requirement

Hi,

We have a requirement to develop a windows app. I have a Macbook. I know that I have to install Windows OS for windows app development. But I am not sure which version of Window I should use. I read some documentation and It's a bit confusing. One link says Titanium doesn't support windows 8.1 Doc1

while other says it supports 8.1

Doc 2

Can anybody tell me which one I should install for windows development.

Thanks.