Pusher : Error (console log)

[openbooknoobdeveloper]

Hi guys I am new to development, go easy with me :) I am 13.

2 questions:

1 - what pusher does ? why it is really important to the exchange?

2 - on my console log i am getting this error.

I alredy registered on pusher and got the code and replaced them on my APP

WebSocket connection to 'wss://api.pusherapp.com/app/46c99999999979dc9995?protocol=7&client=js&version=2.2.0&flash=false' failed: WebSocket is closed before the connection is established.
c.close @ funds-76328736273dvgdsdsdd88b2e99187.js:34

Pusher : Error : {"type":"WebSocketError","error":{"type":"PusherError","data":{"code":4001,"message":"App key 46c99999999979dc9995 not in this cluster. Did you forget to specify the cluster?"}}}
b.warn @ funds-76328736273dvgdsdsdd88b2e99187.js:34

[ysv]

@openbooknoobdeveloper pusher is used by trading-ui for updating of order book and trades

Probably you have wrong pusher credentials