Enable as action is essentially turning on a feature. After you've set up the feature, you would enable it as an action to start using the feature. If enable as action wasn't turned on, the feature would be disabled.
Dec 25 2018 15:03 PST - UPDATE ON SERVER OUTAGE: On Christmas day we had a very large number of new App sign ins causing us to reach an email quota. We have been able to resolve the issue since and we ask you to please try to setup your account again. Thank you so much for your patience and understanding! Happy holidays! Support Availability : Monday - Friday, 9am-5pm PST