Well, you need composer to install Flarum, which some shared hosting providers provide. And also there is a workaround which I won't recommend to a New User (Also you can try Pockethold but idk whether it's a good idea since you can't install extensions). But if you are interested.
- Install Flarum locally using composer.
- Go through the Flarum installation.
- Export your Database.
- Upload the Flarum files, then import the databse.
- Make changes to the config.php, including the new url & database information.
If you need to install Extensions, you have to do it before uploading or you can upload the,
- vendor folder completely
After installing the required extensions. Any wrong step can break your installation, so I'd recommend having a better idea about how Flarum works before you do so.
Oh DAMN! You can Try FreeFlarum too to host your Forum!