Activity Items are assigned to users who must perform certain actions that are part of an organization's procurement workflow. Really, Activity Items can consist of almost any activity necessary for ensuring that the procurement workflow is operating effectively, and can be assigned to any user, including buyer users, suppliers, and workers.
After a work order is created, activities may require completion if the buyer has configured them to be part of the onboarding and activation process. These elements may require review by the buyer, manual completion of a check in the application, or other activation and submission steps as defined in their setup.
The Activity Items tab on a work order displays any activities that must be completed. As illustrated here, the activities must be completed by the supplier before the worker can be onboarded.

The activation step is an ideal time for the program team to review the work order and any required on-boarding tasks and validate that the work order is ready to be activated.