The first workout in the 5k app is an introductory mission to the world of Zombies, Run! This has been ported over from the standard Zombies, Run! app so that users who don't have Zombies, Run! have some idea of why they are training in Abel Township, and being referred to as Runner 5.
This introductory mission is a free form run, without any instructions. Interval training begins on the Week 1, Workout 1 workout.