Hi
I am also facing similar issue. I have installed the configured the Commvault Splunk plugin available at: https://splunkbase.splunk.com/app/5718/ and I am trying to get respective data from Commvalut version-11.24.48.
I have checked the permissions for the user(not a service account) of Commcell it is same as per your shared screenshot still no luck.
Please help me understand the possible reasons it is not accepting the credentials.