I have found several tutorials online that guide you on how to install RabbitMQ from the official package - from rabbitmq site. However those installation instructions failed for me giving some nondescript errors. Here's how I installed RabbitMQ on Ubuntu 18.04 and Raspbian Stretch.
apt install rabbitmq-server
sudo systemctl enable rabbitmq-server
sudo systemctl start rabbitmq-server
sudo rabbitmq-plugins enable rabbitmq_management
rabbitmqctl add_user myUser myPass
rabbitmqctl set_user_tags myUser administrator
rabbitmqctl set_permissions -p / myUser ".*" ".*" ".*"
Optional but important
I needed to install
bcmath as well
sudo apt-get install php7.0-bcmath
systemctl reload apache2