@pkwell is absolutely correct 
If you find yourself consistently failing your VO2 workouts, dial down the intensity up to 5%. You will not want to reduce more than 5% because then you will no longer be utilizing the VO2 max zone that the workout was intended to target.
If you still find yourself failing the workouts, you can try extending the rest periods as well to improve your recovery between work intervals. My favorite way to do this is by using the “Pedal to Play/Pause” feature. This allows you to pause your workout whenever you stop pedalling. This allows you to stop pedalling for some additional time between sets by stopping pedalling (or backpedalling depending on your setup). This allows you to extend the recovery valley without physically interacting with the TR app 