Bosh Concourse error when trying to add external workers | failed to configure SSH server: ssh: no key found - worker

Question

We are having a hard time setting up the cluster for an external worker. I think we don't understand all of the SSH keys that need to be created manually and exchanged. The TSA job errors with
failed to configure SSH server: ssh: no key found.
here is my manifest for bosh:
---
name: concourse
releases:
- name: concourse
version: latest
- name: garden-runc
version: latest
stemcells:
- alias: trusty
os: ubuntu-trusty
version: latest
instance_groups:
- name: web
instances: 1
vm_type: default
stemcell: trusty
azs: [z1]
networks: [{name: default}]
jobs:
- name: atc
release: concourse
properties:
no_really_i_dont_want_any_auth: true
postgresql_database: &atc_db atc
- name: tsa
release: concourse
properties:
host_key: ((tsa_host_private_key))
host_public_key: ((tsa_host_public_key))
authorized_keys:
- ((osx_worker_public_key))
- name: db
instances: 1
vm_type: default
stemcell: trusty
persistent_disk_type: default
azs: [z1]
networks: [{name: default}]
jobs:
- name: postgresql
release: concourse
properties:
databases:
- name: *atc_db
role: postgresql
password: password
- name: worker
instances: 1
vm_type: default
stemcell: trusty
azs: [z1]
networks: [{name: default}]
jobs:
- name: groundcrew
release: concourse
properties:
tsa:
host_public_key: ((tsa_host_public_key))
- name: baggageclaim
release: concourse
properties: {}
- name: garden
release: garden-runc
properties:
garden:
listen_network: tcp
listen_address: 0.0.0.0:7777
update:
canaries: 1
max_in_flight: 1
serial: false
canary_watch_time: 1000-60000
update_watch_time: 1000-60000