To set Automated Due Dates in Practice ERP you must be in the Taskflow Administrator Role. Within that Role you will go under Taskflow Admin, then Configuration and click on Project Types.
Once you are within the Project Type configuration you can filter to the Project Category to find the Project type you want to set the Automated due date on.
If you scroll to the right you can see all the field to set your Automated Due Date based off your Period End information. This functions the same as setting due dates on recurrences within General or Client Templates.