Failing to setup cluster with ansible

[ShadowOfStrelok]

fatal: [localhost]: FAILED! => changed=false
msg: cephadm is the new official installer. Please, consider migrating. See https://docs.ceph.com/en/latest/cephadm/install for new deployments or https://docs.ceph.com/en/latest/cephadm/adoption for migrating existing deployments.

[guits]

I'm not sure what you are reporting exactly. That message seems pretty self-explanatory.
By the way, it means you are using the development branch of ceph-ansible. If you know what you are doing you can still pass -e yes_i_know=true to discard this warning.