I see. I suspect that your local machine has MS office and PDFNet will first try conversion via interop - if Office is present.
Since it this Office is used for heavy lifting, the extra permission for Convert Add-on is not enforced/required. If Office is not present, PDFNet will try conversion via its virtual printer driver (which require’s the Convert permission). Export via Office interop is usually of higher quality that printer driver output. Also please note that PDFNet does not include native/direct support for Office files (so you either need Office or some other app that can print Office files e.g. free office viewers).