Hello everyone. My girlfriend's computer was going crazy, so I'm trying to help her format the computer and clean install Windows 8.1. I downloaded the ISO using Microsoft's media creation tool, I don't remember if it was a Pro or Core ISO. I also completely forgot what I need to do for the installation to work. The installation keeps asking for an activation code and I have no idea what it is. Please help. I'd like to know what ISO I should download and every step to get it working, at least during the installation. I can use the Microsoft Toolkit to activate it once it's installed, I think, I just don't know how to get through the installation process.