Beware of submitting to Amazon Storyteller. You're automatically assigning Amazon Studios exclusive rights over your work for a 45 day window and agreeing in advance the option price.
To use Amazon Storyteller you need to set up an Amazon Studio account and agree to their T&C's.
Alarmingly, you'll be agreeing to assign Amazon exclusive rights over your work. Buried in the fine print here http://studios.amazon.com/getting-started