[ceph-users] How to call cephfs-top

I'm using a dockerized Ceph 17.2.6 under Ubuntu 22.04. Presumably I'm missing a very basic thing, since this seems a very simple question: how can I call cephfs-top in my environment? It is not inckuded in the Docker Image which is accessed by "cephadm shell". And calling the version found in the source code always fails with "[errno 13] RADOS permission denied", even when using "--cluster" with the correct ID, "--conffile" and "--id". The auth user client.fstop exists, and "ceph fs perf stats" runs. What am I missing? Thanks!