@Global Admin 3 Thank you for reaching out to us, could you help us with the error details when you install the agent.
Sharing this for reference - https://learn.microsoft.com/en-us/entra/identity/hybrid/connect/how-to-connect-health-agent-install which helps about the pre-reqs needed while installing Entra Connect health agent.
Let me know if you have any further questions, feel free to post back.