Media server not available in Media Servers tab to add credentials
The Cloud Catalyst storage server can allow access to media servers only if they are Red Hat Enterprise Linux (any version) and have NetBackup 8.1 or later installed. Access is given to media servers by granting them credentials in the Media Servers tab of the Cloud Catalyst storage server properties.
If the media server does not have NetBackup 8.1 or later installed, it does not appear in the Media Servers tab, so it cannot be selected.
See Configuring source control or target control optimized duplication for Cloud Catalyst.