Theres a point in this chapter after you leave the RV park and meet back up with the rest of the group with Luke and Jane in tow. There are a few dialogues to go through but you will eventually be given a choice to follow Jane to the observation deck or to help Mike and Bonnie. Go with Mike and Bonnie and when the next section starts you will be arriving at the museum and the achievement will pop. Regardless of who you choose to go with first, you have to go to both the museum and observation deck to progress the story.