tolgaaaltas This is not the best method here, working around composer to add extensions is merely a short-term solution, because composer is still required for Flarum upgrades and patching extensions when there are fixes or new features. A grey market of extension zip files is not a sustainable approach.
Genji If you're unable to use composer via SSH (and check with your host, they may allow it or can enable it for you), then I recommend you look into Pockethold which comes with Bazaar for managing extensions without having manual files. This may mean reinstalling Flarum, but you can keep the same database and config.php file that you currently have.
If your host will not allow SSH and Pockethold does not work, then I would strongly advise you to find a different host for Flarum (or check out FreeFlarum.com, which is run by a community member). Flarum relies on composer to upgrade, as I mentioned above, and using manual file transfers will create more work than necessary.