You can add the required extra field when adding an individual user in your Adobe Learning Manager account by following the below steps.

-> Login > Admin > Users > Active Fields > Configure Fields > Add the required field for Internal Users > Settings > For Internal Users > Configure active field properties. Here, you can click on the required checkboxes.

Also, please check and confirm your requirement while clicking on the “Multi-Valued” checkbox, as this checkbox cannot be undone after the system creates usergroups for the associated field.

Please refer to the screenshots below.