The My Cloud’s embedded media server (Twonky) is a basic media sever. It is NOT like Plex media server/client or the Kodi client. You can use the forum search feature, magnifying glass icon upper right, to find past discussions on how to try and add Plex to either the first gen or second gen single bay My Cloud units. The multi bay My Cloud units that support third party apps generally have Plex add on module support.
https://community.wd.com/t/new-release-plex-media-server-version-1-7-2-06-13-17/208577
Or one can setup Kodi on a Kodi supported media device that is connected to their TV.
Generally the My Cloud relies on the device client (in your case your Samsung TV) to display the content on the TV. One should check to see if there TV or device supports a different DLNA media client that can be installed to the device.
You may also want to see the other recent thread discussing Samsung TV"s and the My Cloud as it may be relevant.
https://community.wd.com/t/wd-my-cloud-4tb-with-samsung-smart-tv/208661/
It is also advisable to read through the following discussion to get the most out of the Twonky media server embedded within the My Cloud.
https://community.wd.com/t/faq-twonky-dlna-media-server-setup-use/95373
