Sorry for the delayed response and inconvenience caused. AS per the description, I can understand that when you convert a PDF to a TIFF, you are getting a multi-page zip, Is that correct?
When you convert a PDF document to TIFF, PDF pages content will be exported/converted to an individual image and This is the reason you are getting a multi-page zipped file. This is designed behavior and it cannot be changed.
To know more about Adobe PDFPack, you can refer to Adobe article FAQ | Adobe PDF Pack
Feel free to update this discussion for any further assistance.