Week 4’s free battle star can now be collected for if you have completed all of the Week 4 challenges. If you following hint given when you unlock the week 4 loading screen, you will see the hint to the location on the wall, in the back of the picture. See below:
Week 4 Battle Star Map Location
It’s located at G9 on the Fortnite map, north-east of Lucky Landing on the head of the statue. Once you see the star, simply interact with it to receive 10 Battle Stars (full tier).
Below is a screenshot of the Fortnite Battle Royale map, which shows the exact location of the battle star. Remember this star will only show to players who have completed all of the Week 4 challenges.
Map Coordinates: G9