As quoted in that topic you need to first create a website on cyberpanel for your subdomain.
Secondly, setup your nodejs app via the ssh terminal under /home/myslickdomain.com/public_html or where your document root is and assign a free port 3000, 3001, 3002 etc
Thirdly setup context for the app so that 123.456.789:3000 nodejs app is read by your users from myslickdomain.com
Kindy try these steps and revert back.