The Data Platform service account, used in the Authentication Settings page in the 'Populator'->'Admin account' property, must be a member of at least one Active Directory group other than 'Domain Users'.
If the service account is only a member of 'Domain Users', then the test results will show the error 'Admin account not found. Check your populator settings or admin account and try again.'
According to Flexera Support, this is a limitation of the Pentaho component on the User Console server.
