In a terminal, try:
clojure -Sdeps '{:deps {github-johnmn3/cljws {:git/url "https://gist.github.com/johnmn3/a845f2bf67ad877d957bccd7f9cefe8c" :sha "4559f6d93509da4023c4df25965ddde004566b95"}}}' -m cljws chat-server localhost 8899
Then, in another terminal, try:
clojure -Sdeps '{:deps {github-johnmn3/cljws {:git/url "https://gist.github.com/johnmn3/a845f2bf67ad877d957bccd7f9cefe8c" :sha "4559f6d93509da4023c4df25965ddde004566b95"}}}' -m cljws client ws://localhost:8899
Repeat the last step in as many terminals as you like in order to add clients to the chat server.