Fortnite Chapter 2 Season 4 Week 5's challenge to get closer to Wolverine's skin is to locate a Mutant Containment Truck. What you're looking for is the Trask Transport Truck lair which is in the north of the map, just southeast of Lockie's Lighthouse and northeast of Coral Castle. You can find the exact location shown on the map below.
When you reach the truck, which is all you need to do to complete the challenge, you will find that the back door has been kicked out and everything inside is now free. It was actually Wolverine who was kept in the truck, and he can now be seen wandering around Weeping Woods trying to rip people's faces off.
Wolverine and Trask Industries actually have a lot of history, as it was Trask who built the large robotic Sentinels used to hunt down mutants in the X-Men universe, and Wolverine is uniquely adept at shrinking them down to size.
Completing this challenge will unlock the MCG Wolverine style and bring you one step closer to finally unlocking the Wolverine skin next week, October 1st.
Don't forget, there's a new set of Challenges available for Week 5, offering plenty of ways to get XP and rank up your Battle Pass.