PS4 online multiplayer is free for all, this weekend only.
You have from 7:00 PM (19:00) AEST Friday 24th June until 7:00 PM (19:00) AEST Monday 27th June 2016 to play online at no cost.
PS4 Firmware v3.55 has just been released (300.7MB), so make sure you update beforehand to maximise time. You wont be able to go online without updating first.
Thanks OP; hopefully I can rack up some hrs playing SW Battlefront online