Approval Rule for a specific Document of Record

Summary:

Approval Rule for DOR with a specific document that should be auto-approved and an FYI to the employee

Content (please ensure you mask any confidential information):

We have requirements from our customer listed below:

• Worker's current assignment manager will add a specific document and it should be approved but an FYI will be triggered to the worker
• and specific document type should be included in the rule as well.

How do we mention worker's current assignment manager instead of a role specific of Line Manager? And what is the condition to use for a specific document?

We have used the below expression but it failed saying the attributed in the rule has a null value -