How do I get an installer for MacOS without already owning a Mac?

Yes. The macOS full installer is only available from the Mac App store on a Mac. There is no other place to get macOS installers. Its also free.

Also it is a violation of the macOS operating system terms of service and license to install macOS on non Apple hardware.

JWBstuhr wrote:

I'm stuck.

I'd like to get an external drive to boot MacOS from, but here's the thing:

I don't own a Mac, so I can't create installation media.

If you can't pay online for a file, I'm fine with paying for a CD.

But there's a problem with that: I can't find any installation CDs / I don't know what to look for.

Please help, and thanks in advance.

That is not possible.

CD installation has gone the way of the dodo bird , not to mention

Apple does not do OS only licensing ...

Correct. Well, by Apple.