If all content versions are not visible, then you need to make the below additional settings:


  1. Go to Setup and search for Permission Sets (choose an existing one or create a new one).
  1. Click on the App Permission, then Content.
  1. Select the "Query All Files" option.
  1. Assign the newly created permission set to the user who has a Mass File Download license.

Note: Query All Files is not enabled by default for the admin user, but you can at least enable it in a profile/permissions set.