When setting up the Approval Workflow you'll be able to attach a PDF to the Assignee Email, Rejection Email and Approval Email notifications. To do this check the appropriate PDFs under the Attach PDF(s) setting. Be aware that Gravity PDF Conditional Logic is not supported and the PDF you setup will always be attached to the email.
User Input Workflow
When setting up the User Input Workflow you can attach a PDF to the email notification. Like in the Approval Workflow, check the appropriate PDFs under the Attach PDF(s) setting. Gravity PDF Conditional Logic is also not supported in this Workflow.
As this Workflow actually sends the standard Gravity Forms Notification, Gravity PDF is fully supported – including Gravity PDF Conditional Logic. All you have to do is configure Gravity PDF to attach PDF(s) to notifications and select the notification(s) you want to send in the Workflow.
From Gravity PDF v6.8, a View/Download PDF metabox is displayed in the sidebar of the Workflow Inbox – in both the admin area and block/shortcode. The metabox will only display for logged-in users with a valid capability.