Hi!
Yes, it is perfectly normal to have to stop a lot during these workouts, they are tough going, so don't worry about that and keep working as hard as you personally can, you aren't competing with the people on the screen. The results will then follow for you.
If you are able to get all the way through the warm up without a break already, I reckon you are doing pretty well - it took me about 3 weeks on the full schedule before I could manage that!
Best of luck with your journey

Hugh