Will and his Spacerex channel on Youtube is your best Synology NAS resource to get setup before installing Plex.
If you have trouble opening Plex for the first time, use this url by inserting your own local IP addres for your Syno NAS.
http://server.local.ip.address:32400/web
Like my example in the video...
http://192.168.68.116:32400/web
Where to get the Synology package install for and Syno NAS with an 64 bit Intel or AMD CPU.
https://www.plex.tv/media-server-down...