Find a way into the Resort
Once you've managed to escape the trap and find Abby's location, head forward and take down the enemies roaming the area, then go through the area whilst using the buildings to get resources and cover. After you reach a red train, open it and go through then climb the ladder to see where the Prisoners are being taken.
Drop down and hug the left wall to find an Artefact 116/117 sitting on a barrel, then crawl underneath the blue train and open the fence to get inside the Resort.
Explore the Resort
Here you'll want to sneak around the area whilst freeing the chained infected, then sit back and take down the enemies whilst they're distracted. Once the enemies have been dealt with, head into the wooden building to find the final workbench.
Prepared For the Worst
Find all workbenches
From here, go into the building ahead and you'll find the final Trading Card 48/48 in the game by the radio, now head through the building and climb out the gap in the wall to reach the next section of the Resort.
Like before, free the three infected, then sit back and take the enemies out whilst they are distracted, now head up stairs and grab the last Artefact 117/117 from the bedside table. Finally, go outside and take the enemies down to the left, then go downstairs and free the prisoners.
After discovering Abby's location, follow the path ahead until you reach the beach then free Abby from the pillar. Now follow her down to the boat for a cutscene.
Finally, you'll have one last fight with Abby, so like the previous melee battles you'll want to go in for a couple hits at a time, and then dodge her two swings before striking again.
Once you've returned back to the farm after the events with Abby have concluded, head inside and interact with the guitar one last time to wrap the story.