You don't need to have an existing paid license(1), but you do need to run it on Apple Mac hardware. Non-Apple hardware and VMs are not supported, don't work without some significant hacking and are forbidden by EULA.
(1) Practically speaking if you have a machine capable of running this legally, you also have an existing paid license for MacOS, so this is mostly a theoretical difference.
(1) Practically speaking if you have a machine capable of running this legally, you also have an existing paid license for MacOS, so this is mostly a theoretical difference.