I have (had) a Promox 8.1 cluster with 2 nodes and one qDevice as 3rd witness
/etc/ceph/ceph.conf
[global]
     auth_client_required = cephx
     auth_cluster_required = cephx
     auth_service_required = cephx
     cluster_network = 10.227.101.33/24
     fsid = something...