What are the different users in the BPM workflow and its functionality?

Summary:

We are currently having an issue wherein the original approver does not receive any notification. The delegatee (assigned) approver based on the BPM Vacation Rule is receiving a notification but the original approver does not. What will be the set-up in the notifications wherein the original approver can receive the notification when he delegated the approval. We would like to know the different users in the BPM Workflow and to where we can input the set-up so that the original approver will receive the notifications.

Content (please ensure you mask any confidential information):

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