Unable to Configure Plex Media Server on WDPR4100 mycloud OS 5

Hi There,
I have updated my WD PR4100 NAS to the latest firmware 5.11.112 and I am trying to configure Plex media server but I am getting stuck on the configuration section.
I have installed the latest Plex media server (PlexMediaServer- but when I click configure it does redirect me to the web login, then I login with my plex account fine, when I click on “Add your media”, it keeps asking me to “Get plex media server” See attached screenshot. the link shows the NAS IP address as it should.

I am confused and don’t know how to proceed. I was wondering if anyone else is experiencing this issue. Thank you very much in advance.
Kind Regards,