Hari it's still related to Flarum, so IMO it's probably best to keep the discussion here. This will make sure that others (not necessarily FreeFlarum users) can see this discussion and get help. FreeFlarum's thread is mainly intended for things related to FreeFlarum (e. g.: forum down, an error occurred, etc. - we do not have the capacity to always offer an all-in-one help for Flarum).
Anyways, here's what I know:
- Go to Pusher.com.
- Click on the "Get your free account" button.
- Complete the Sign Up process.
- Use "Channels"
- Name it how you want, it doesn't matter. Select an Europe cluster (close to yours/FreeFlarum's server). Don't tick the "Multiple environments" checkbox. Frontend can be set to "Vanilla JS", backend to "Laravel" (I think that doesn't matter, your main objective here is to obtain the credentials)
- On the left sidebar, click on "App Keys"
- Copy the credentials from that page to your Flarum Pusher configuration (the values in quotes, without quotes)
I tried to make it as detailed as I could. I hope it helps. But you can also browse some existing threads for further details/help.