Here is from the training plan page –
Tips: Rest when you are tired. If you miss a workout do not try to make it up. Just move on. If you miss more than 2 in a week then repeat that week. Do not increase the intensity and hope to gain more benefits. There is no short cut to when it comes to aerobic adaptation.
Assuming you missed workouts in Week 6/7, you might want to repeat these weeks. I would reassess the volume if you feel fatigued.
Hope this helps.