I have a WD my cloud WDBCTL0030HWT and I would like to know if there is the possibility of installing the Plex application on this device.
No.
Plex do not provide an image for the basic MyCloud.
The basic MyCloud processor is not powerful enough to support the video transcoding required by Plex.
http://community.wd.com/t5/WD-My-Cloud/Plex-for-personal-cloud/m-p/875593
http://community.wd.com/t5/WD-My-Cloud/Using-Plex-Media-Server-with-My-Cloud/td-p/824681
http://community.wd.com/t5/WD-My-Cloud/Plex-Media-Server-on-WD-my-cloud-4Tb/m-p/629285
