When the trigger event happens and the flow is On:

1. Sprwt saves a snapshot ("metrics") of the customer and the event data (order details, subscription, etc.) so the emails can be personalised.
2. Starting from the first block, every Email and SMS step is placed in the sending queue with a send time; Time Delay blocks push later steps' send times forward; a Conditional is queued for evaluation after its wait time and the steps behind it are queued only after it is evaluated.
3. Email steps are skipped for customers whose Receive Email is off, and queueing stops when your plan's monthly email limit is reached; SMS steps are skipped when Receive SMS is off or SMS limits are hit.
4. The background sender delivers each message when its time arrives (the same queue as campaigns, up to 50 messages per run).

The same customer can enroll again each time the trigger fires (e.g. every order), which is why the Analytics modal shows both unique and total enrollments. Flows do not enroll anyone if onboarding is incomplete (Onboarding Pending!).