how to add department manager to workflow?

Summary:

We are trying to add department manager (not cost center manager) to approval flows for project expenditure batches.

Content (please ensure you mask any confidential information):

How do we add the named department manager in manage departments setup to approval flows?

Version (include the version you are using, if applicable):

23D

Code Snippet (add any code snippets that support your topic, if applicable):

NA