Approval Variables are an Advanced Approvals object. Simply put, they are a number that represents the result of evaluating multiple records and can be compared to roll-up summary fields.
If Dynamic approvals within Advanced Approvals package for Salesforce CPQ don't work with delegate approvers find out in this blog post what might be causing this issue.
You have to keep in mind certain important things regarding approval chains when you submit any approval that has multiple approval chains and unchained rules.
When we create an Approver record, we can assign it to a user in Salesforce or a group of users. It is also possible to set up dynamic approvers based on more complex criteria.