Enabling the ability to upload designees is controlled through permission configurations for Admin Security Groups.

The permission that controls this is called:

"Donations - Designated Giving"

The default setting is:

Manage Designees:
Allow administrators in this group to create, edit, and view designees.

To allow for designee uploads it must be set to the following:

Manage and Upload Designees
Allow administrators in this group to create, edit, and upload designees.

This can be adjusted for a specific security category (add an override) or changed site wide.