What's the best way to play a sound on join if the sound is already playing?

What do you mean? Explain your question better and give some code.

I don't have code becuase I don't know how to do it, and another explantion is : If you join a club and music is playing when you join you won't be able to hear it since it started playing before you joined, and you will continue to not hear it until the sound stops and plays again.

These are sounds played in the PlayerGui so each individual player hears their own version. Usually you can hear the music in Workspace once you join. The way to get around this is possibly copying some else's music and adding it to that player that just joined?

I'm not quite sure how you could get around the player joining other then tracking the exact TimePosition

So its possible through playergui?

I suppose it would be

Easy, you just set the TimePosition when you start playing the sound, then resume it. It will continue from the TimePosition, and will stop with everyone else's sounds when it is time.

^ In a game.Players.PlayerAdded function correct?

Yes. Most likely, you would want a big handler in ServerScriptService that accomplishes what you want. I could make answer for it, if you want?