Configured APM agent and it is not checking in.
Release : 21.2.x
APM: 10.7.0.358
Wrong port in use and had to mark the agent as 10.7 compatible.
The port noted is 5001 for the Enterprise Manager:
https://techdocs.broadcom.com/us/en/ca-enterprise-software/it-operations-management/performance-management/22-2/integrating/monitor-server-performance-with-ca-application-performance-management.html
See the following for troubleshooting agents not checking in to APM and having the note regarding forcing compatibility for older versions of APM:
https://techdocs.broadcom.com/us/en/ca-enterprise-software/it-operations-management/application-performance-management/22-1/troubleshooting/agent-troubleshooting/Agent-Starts-Not-Visible.html