1. Click on "Workers" in the top row
  2. Click on "Workers"
  3. Find the worker in the list, and single click to select them
  4. Click "Add User Record" at the top of the page
  5. Click on the "Security Groups" field and select the group to which the worker belongs.  Repeat this step to add any other groups necessary. See Which Permissions Groups to Assign to User
  6. Click "Save"

  7. Remember to revisit Worker Setup to make sure all items have been completed.