Can't get run on server event to execute in actor

I got the variable to replicate and it works now but is there anything I can use other than (GetPlayerController Index 0) for the overlap? because while it works for the first player, it doesn’t for the second player. I guess because the second player has a different index? or will this not be an issue if I was using two separate computers? though it makes it a little hard to test features.

Thanks for your time and comprehensive answer.