You will need to create two files:
garrysmod/data/metaconcord-endpoint.txt
with the hostname and port to the websocket server that node-metaconcord will host.garrysmod/data/metaconcord-token.txt
with a custom secret of your choosing that node-metaconcord will accept for incoming connections.
Of course, you'll need the node-metaconcord service to be running on your server to allow for communication with this add-on