Samsung Plex app not working

I have the same issue. Plex Client will no longer connect to the PMS.

Old UE46F6500 from 2013.
The Samsung pre-Tizen Plex Application has been deprecated.
It was a gift from a developer - Orca.
It is no longer on the Samsung Smart Hub available apps.
I stupidly deleted the app. version 2.013 which worked fine last week
Believe I can now only access Plex Client by side loading.

Either run app from from USB Stick or…
Sync with Apps in reinstall.

see - No Samsung TV App on Smart TV Hub