Adding subscribers to your automation
By default, imported contacts do not receive your automated campaigns. If you click on your automation's trigger, you will see the option "Run on imported contacts".
If you set this to On and click Save & close, your imported subscribers will trigger the automation. Be aware that you need to set this to On before you import the subscribers, or they will not receive your automated emails.
Once a contact receives the last campaign of the automation, they're removed from it and will not receive any future campaigns added there. When campaigns are added to the automation, but a subscriber is already past that step in the automation, that campaign won’t be sent to them.