You do a full Metashape Pro install, but when you run the installed executable with the --server flag it doesn't check for a license.
After previously running the server on Windows, I recently set up a headless Linux VM to run our server. The process worked fine, the only thing that was a little annoying about not having a minimal 'server' installer was the need to install a bunch of GUI libraries on a machine that will never have a graphics display or do any processing. All in all it was pretty easy to get setup though and has been working well.