What “apps” are you using or looking at that are not “officially compatible” with this device (I assume you mean the My Cloud)?
All one needs is a DLNA client and they can access, through the local network, the embedded media server within the My Cloud (Twonky).
The problem with using Plex on the My Cloud is that transcoding, a major feature of Plex, is not officially supported due to the low powered hardware used on the My Cloud. See the Plex NAS Compatibility Guide for more information on the limitations of Plex on the various WD My Cloud models.
While the following post is for the v4.x My Cloud it may possibly give pointers on how to possibly install Plex on a v2.x My Cloud using SSH.
http://wdstagingsplit.staged-by-discourse.com/t/using-plex-media-server-with-my-cloud/94429/13
