Related Questions:
Add attachments to a Workflow
Environment:
Event Temple Web App
Answer:
When you apply an Email Template as a step in the workflow, the email will be sent automatically to the customer at the scheduled date along with any attachments on it.
You will need to ensure any attachments are first added to the chosen Email Template
For example, this email template has a .jpg attached:
When I choose this email template as part of a Workflow, the same .jpg will be attached.