rriivasss do you have a public static IP address that's accessible from the internet ? Are you using that public IP in your Cloudflare settings ?
Unless you're using Cloudflare Argo (I think that's the name of that product) you can't proxy to a local IP address.
An SSL problem will probably result in an error message making it clear SSL is the problem, it doesn't sound like it's the case here.
Does it work if you set the public static IP in the hosts file or at another DNS provider, or at Cloudflare without proxy enabled ?
As for the "something went wrong error", it could be multiple things: The Cloudflare branded page, in which case you probably have a wrong IP setup in Cloudflare. Or if it's a red banner: It could be a client-side error in Flarum, in which case the browser console or network tab might contain more details. Or it could be a Flarum backend error, and you'll find the details in Flarum log files.
If you're encountering issues with Flarum, you could temporarily enable debug mode in config.php to see what it says directly on the page. Don't forget to disable debug mode afterwards.
Also you're mentioning a tutorial, could you maybe link it ?
