My book to my cloud?

Hello, first time poster here… can anyone tell me the best way to bring my old MyWorldBook 2TB NAS Raid up to date so that I can load Plex software and use it as a media server ? The drives are physically fine, but I feel like it needs a new operating software.
Thank you in advance for any suggestions.

Unfortunately, My Book World edition supports only TwonkyMedia™ server application and WD TV Live HD Media Player to stream your media content.