I have an older MacBook Pro that had some HDD issues. Now the Mac doesn't have a working OS and I need to install MacOS. The newest version that it can use is Mac OS Mountain Lion. So I borrowed a friends new MacBook, logged into the Mac App Store with my Apple ID, and the bought it.
But now I can't download it because when I click download, it says this version of MacOS is not compatiable with the newer MacBook.
Which is fine, but I'm not trying to install it on the new Mac, I just want to copy the install over to an external hard drive so that I can then use it to install macOS on the older mac.