It’s a preview as far I know. Someone else linked to it in another thread.
https://artifacts.plex.tv/plex-desktop-alpha/1.4.0.924-60046db9/macos/Plex-1.4.0.924-60046db9-x86_64.zip?_ga=2.105113859.1407299009.1573180259-1763143486.1555638702
