The import wizard only works when the source app (Outlook Express) is installed on the same computer

The import wizard only works when the source app (Outlook Express) is installed on the same computer as TB. Since WXP doesn't support TB higher than v. 52, there wouldn't be a case of TB 60 or 68 and Outlook Express on the same computer. Still, you can import eml files from Outlook Express to TB 68 by drag and drop from an Explorer window to a subfolder of Local Folders in TB, or with the ImportExportTools NG add-on.

See the 3rd item in the Advanced alternatives section here.