Pusher for Realtime Notifications
In order to use the chat functionality within your development environment, you will need to sign up for a free-tier Pusher account and retrieve its keys. Then you'll need to provide those keys to the Rails application.
Once signed in, fill in the prompt to create a new Pusher Channels app.
In your new Pusher Channels app, click the "App Keys" tab.
Change your keys accordingly (name of Pusher key -> name of our application key):
app_id -> PUSHER_APP_IDkey -> PUSHER_KEYsecret -> PUSHER_SECRETcluster -> PUSHER_CLUSTER