It’s been approved by Google but these releases are staged so it will not be available to everyone immediately.
If you need to you can download the apk and install it manually: https://downloads.plex.tv/plex-media-server-new/1.41.3.9292-bc7397402/android_server/PlexMediaServer-1.41.3.9292-bc7397402-7492-bc739740-shield-arm64v8-samba-release.apk
