As you are already running a version of Docker with inbuilt support for Docker Swarm, there isn't anything you need to do to install Docker Swarm; you can verify that Docker Swarm is available on your installation by running the following command:

$ docker swarm --help

You should see something that looks like the following Terminal output when running the command:

If you get an error, ensure that you are running Docker version 1.13 or above; at the time of writing, the current version of Docker is 17.03.