This may be caused by the following issues:

• The clock on your host is not synchronized with the OCI platform. You'll be unable to install a management agent if your host's clock is skewed more than five minutes from the OCI platform. For more information, see Maximum Allowed Client Clock Skew.
• Ensure you have read the Management Agent documentation and confirm that you meet the prerequisites. In particular, your host must meet the Generic Prerequisites for Deploying Management Agents, including the requirement for JDK 8 (update 281, JDK 1.8.0_281, or higher). The management agent is not compatible with any other versions of the JDK.