This release of ES does not include a tool for migrating existing MSS users, defined in the Resource Definition (RDO) file dfhdrdat, to LDAP user classes other than microfocus-MFDS-User. The cas-to-ad tool that is used by es-ldap-setup can only create Micro Focus user objects.
If you have a significant number of MSS users (who are not already Windows users) to migrate, you may want to use the casrdtex utility to export the RDO definitions to a text file, which could be processed into an LDIF file using a scripting language such as Perl.