Q: How do I get windows on mac with a windows license product key?

it's not something one can describe in a quick post

How to install Windows using Boot Camp - Apple Support

install windows in bootcamp

https://www.youtube.com/watch?v=2S5YM-TQ-nc

Windows is a Microsoft product. Why don't you ask your friend who works at Microsoft.

get a windows iso

You will need a Windows PC. The exe file is a Download Manager. Run it on the PC, enter your Product Key and you can download the Windows Installer to a USB and/or DVD and/or ISO. Once you have the ISO file follow the links from Rudegar to install Windows. If your Mac has built in Optical drive, create a physical DVD using Disk Utility (Yosemite): Burn a disk image to a CD or DVD .

It may be too large for Skype, but he could use Dropbox or similar to send it to you.

It depends on the Skype connection bandwidth. The ISO file is about 4GB.

Is your ISO a combined 32-bit and 64-bit ISO? You need one or the other, a combined one will not work in BCA.