Click the three-dot on the Phase that you want to add the Work Categories to.
Click Add Schedule Item > Add Work Category
Work Categories can only be added to Phases when the Phase Time Tracking setting is configured to "Track Time By Work Category."Click Add Custom Work Category to create a new one.
Once the custom Work Category is created, you won't be able to delete it completely from the list, but you can rename it.Enter the custom Work Category name and select if it requires additional description and if it's billable or not.
Click Create
The modal will close, you can find the new custom Work Category in the list.
Select the Work Category and Click Done.
The Work Category will show under the Phase or Subphase