The Grouper Messaging system interface will have a RabbitMQ implementation.
Install RabbitMQ
On windows, install erlang, then install RabbitMQ
C:\Program Files\RabbitMQ Server\rabbitmq_server-3.6.10\sbin>rabbitmq-plugins.bat enable rabbitmq_management
Restart RabbitMQ service (e.g. in windows in local services console)