SLY Designs, the only reason that the "Add Customers" link wouldn't show on the Customers tab in your admin is if either (a) you didn't copy /includes/extra_datafiles/add_customers_filenames.php, /includes/functions/extra_functions/init_add_customers.php and /includes/languages/english/extra_definitions/add_customers_name.php into your admin directory or (b) you copied the /YOUR_ADMIN directory contents to your store's root directory without renaming /YOUR_ADMIN to match your admin's "secret name".

The install for the v1.5+ series happens automatically via /YOUR_ADMIN/includes/functions/extra_functions/init_add_customers.php, so those are the only two reasons that I can fathom for the tool not showing up in your admin toolbar.