No Qemu Guest Agent error

after installing qm-guest-agent on my proxmox server.

You have to install it inside your guests/VMs and not on the PVE-host. (And also enable it under: YourVM -> Options in PVE.)
Or do I misunderstand?
 
Thanks, so how can I install it inside my guests/VMs. I have a zentyal server I can't install it there. I already do it for my pfsense server and it works.