NOTE: This is only applicable to version 12.0.15 and higher as support for installing as non-root user was only added starting CA Directory r12.0 SP15. Any previous version are still required to be installed as 'root' user.
Even though user 'xyz' is created and you are currently logged in as that user and also confirmed that this user has a description of 'DXserver Administrator' defined properly, installation of CA Directory on Linux still fails with:
User xyz has to be created with description "DXserver Administrator" in case of non-root install/upgrade/uninstall. Exiting the operation.
Most probably this is a centralized user. To confirm, run the following command:
grep -c "DXserver Administrator" /etc/passwd
If the user is present locally on the server, it should return '1'.
If the user is centralized, it should return '0'.
If you get '0' as an output, possibilities are you are installing version 12.0 SP15 or higher where installing as non-root user is supported but that non-root user has to be local. Centralized user is not support in 12.0 version of CA Directory while the support for this enhancement was added in 12.6 release. So the solution would be to use CA Directory 12.6.x version if you cannot have this "DXserver Administrator" defined in /etc/passwd file.
Some embedding products have additional installation requirements that may override the ability to use a non-root user. One example is the Identity Manager Provisioning Directory component. The Provisioning Directory requires being installed as ROOT as well as being installed as the same user that installed CA Directory, meaning that the CA Directory deployed for an Identity Manager Provisioning Directory will need to be installed as ROOT. Please see KB 33190 for a walkthrough of a simple IDM deployment on Linux: 33190 - Linux Install Guide for Identity Manager