The Service Manager log shows:
20211011/135255.956 - U00022070 CAPKI Library not available.
Based on this, it looks like CAPKI is not being used - this is a program that "forces" TLS 1.2 encryption between Automic components. The options are to either install CAPKI or to:
1) Log into client 0
2) Open UC_SYSTEM_SETTINGS
3) Update the key SMGR_SUPPORT_LEGACY_SECURITY to have value 1 set to Y
Then it should be possible to right-click on the agent in administration perspective and choose "Update Service Manager Link". Then it will be possible to start agents from the Administration perspective.