The Activation Email field allows automatic activation emails to be sent to your new sub account members. In order to make this happen, you must populate this email subject field.
Go to the MY ACCOUNT page after logging in.
Step 1. Create a Subject for your new sub account activation emails and enter it into the Email Subject field, then hit the UPDATE button.
When each of your new sub account users signs up, they will receive an activation email with this subject in the email.