On the controller01 node, add the LBaaS v2 service plugin to the existing service_plugins list found in the Neutron configuration file at /etc/neutron/neutron.conf:
[DEFAULT]
...
service_plugins = router,neutron_lbaas.services.loadbalancer.plugin.LoadBalancerPluginv2
Be sure to append to the existing list of plugins, rather than replacing the list content, to avoid issues with the API and existing network objects.