I am not familiar with a Mac, but I migrated Plex server from Windows server 2019 Essentials to a Qnap NAS.
Copied all libraries (folders to the Nas). Installed Plex server on nas. At the same time My plex server on the Windows server was still running. Plex server on the NAS scanned all libraries within a couple of minutes. All went wel… Both NAS and Windows Server were on the same local network.