We use pusher for making your chat work in realtime. So in order to have that functionality, you will need to make a pusher account.
Visit Pusher official site. Create new account or login with existing one.
After login you will see the screen for option to create Channels or Beams. Select Channels and create your first channel that you will use in your website.
Click on your channel that you have created and after that select App Keys. The credentials will be auto generated.
Now lets add these credentials in your Site Settings → Apps & plugins → Pusher live notifications
Please note that you can use OpenSource alternatives, and run them on your server if pusher cost is too much.
You can read more about them here
https://laravel.com/docs/10.x/broadcasting#open-source-alternatives