In the AssignedTo field inside Azure DevOps you can only select a specific user. This means that you are not able to assign work items to a group(TFS or AD group) out-of-the-box. There is no way to change the existing AssignedTo field but you can add your own extra field:
- Go to Organization Settings.
- Click on Process
- We need to create an inherited process. Click on the … next to one of the built-in processes and choose Create inherited process.
- Specify a name for the inherited process and click on Create process.
- Now we can add a new field that allows group identities to be assigned. Choose the work item type where you want to add the extra field e.g. Task
- Click on New field.
- On the Add a field screen, specify a name and set the field type to Identity.
- Go to the options tab and check the Allow assigning to groups checkbox
That’s it! The new process can be applied to an existing project that used the same parent process.