Websocket Integration

I have a script that has web sockets integrated. The script is installed on an Ubuntu VPS server running CyberPanel. Websockets will be integrated in a flutter application and the API for this script has been implemented for android and iOS. 
(Developers not available anymore). I have followed the documentation to implement websocket but not sure if I did the correct steps and I do not know how to test if I did things correct as per the instructions provided later in this document.

I will forward a document to interested freelancer detailing what I want.