The Workflow Task Manager can be opened in the New UI or the Classic UI. In the New UI it is called Workflow Task Manager. In the Classic UI it is called the Work List Task Manager.
To open the Workflow Task Manager in the New UI:
You can open the Workflow Task Manager by opening a Workflow Task Manager Widget or by
opening the Workflow Task Manager in a new tab by opening the Feature sidebar, opening
Administration, and selecting Workflow Task Manager.