ProxyConf fails with a permissions error.
VMware Backup Proxy was not deployed with the VMC option.
Following permissions are missing:
Go to vCenter Server > VMware Backup Proxy > Configure > vAPP Options.
Look into the 4_ 4_VMC option. If it is set to False, VMC is disabled.
Re-deploy VMware Backup Proxy using VMC Option checked during VMware Proxy Deployment.