Welcome to the Serif Affinity Forums, @m Lynch. Like the ‘coreskills’ download, all workbook project downloads are delivered as zip archives with a URL of the form https://affin.co/{projectname} but (as you may have noted in the case of the ‘coreskills’ file) there is no .zip extension in the URL. When you unzip the Mam Tor download you will find two files: a *.afphoto file and a *.tiff file.