SAP Replication Server and Replication Agents do not support replication from SAP Business Suite on DB2 z/OS. You did find the correct information, although the latest can be found in the SAP Replication Server 15.7.1 SP303 documentation.
Supported primary databases:
Adaptive Server Enterprise (ASE)
Oracle
MSSQL
DB2 UDB
Terminology:
Replication Agent is a generic term used to describe the Replication Agents for SAP Adaptive Server Enterprise (SAP ASE), Oracle, Microsoft SQL Server, and IBM DB2 for Linux, Unix, and Windows.
The specific names are:
RepAgent - Replication Agent thread for Adaptive Server Enterprise
Replication Agent for Oracle
Replication Agent for Microsoft SQL Server
Replication Agent for IBM DB2 UDB
* note that the term DB2 UDB is short for "IBM DB2 for Linux, Unix, and Windows" - this does not include DB2 z/OS