Each Workout includes the prescribed cardio for the day in the title. If a workout says “High Intensity Interval Training” then no extra cardio/running is required, since the HIIT circuit is programmed into the days workout! You can run or do extra cardio on those if you’d like, it will give you more wiggle room to eat/consume more calories In the day.
If a workout says “Low Intensity Steady State Cardio” the recommendation is to run/bike/swim for 30-60 minutes at a steady, but manageable pace.
Every Sunday I programmed in a rest day. You can add in your missed workout on Sundays if you want but don’t stress it. Your body needs rest and recovery so don’t shy away from taking a break.