On the support portal at support.broadcom.com, there is not an option to directly download CA LDAP for z/OS
Release : 15.1
Component : CA LDAP SERVER FOR Z/OS
CA LDAP server r15.1 can be downloaded from the CA Top Secret, CA ACF2, or Identity Manager download pages
For example , for under CA Top Secret, go to:
https://support.broadcom.com/download-center/product-download.html?subfamily=TOP%20SECRET
The documentation for LDAP can be found at
https://techdocs.broadcom.com/content/broadcom/techdocs/us/en/ca-mainframe-software/security/ca-system-z-security-communication-servers-dsi-ldap-pam/15-1.html