The low end My Cloud units can handle Plex in general, where they struggle is with the “transcoding” aspect. If all your media is in a streaming client supported format the Plex media server does not have to perform transcoding. As such that limitation isn’t much of an issue.
https://support.plex.tv/hc/en-us/articles/201373823-NAS-Devices-and-Limitations
Plex NAS Compatibility Guide:
https://docs.google.com/a/plexapp.com/spreadsheets/d/1MfYoJkiwSqCXg8cm5-Ac4oOLPRtCkgUxU0jdj3tmMPc/
See the following past discussions on installing Plex to first gen and second gen single bay/single drive My Cloud devices:
https://community.wd.com/t/wd-mycloud-gen2-enable-apps-install-tab-apps/177885/
https://community.wd.com/t/using-plex-media-server-with-my-cloud/94429/
Another option is to have a secondary device/computer running a Plex media server. Its what I did for a while before using the My Cloud. With the My Cloud one can configure the Plex media server to use the My Cloud as its media library. Down side is one would have another device running rather than having the Plex media server hosted on the My Cloud.
