The third step in creating a Phish is Email Attachments.
This is an optional step and does not need to be included when creating a Phishing Simulation.
The 'Email Attachment' is a spoof attachment that can be attached to a Phishing Simulation. This can be used to test if a user downloads an attachment.
To add an Email Attachment, you can follow the steps within this article: What are the Email Attachments in Phish?