All downloadable products from Tapspace are delivered electronically via the internet using the .ZIP file format. Some antivirus software applications re-name files with .EFW extension when downloading. This can happen if you are using Internet Explorer and click on the download line and choose Run instead of Save. Try using the Save option instead, and save it to a location that you can navigate to easily (like your desktop). This should result in the proper .ZIP file extension.
If you save the file and notice that it's still given the .EWF extension, simply rename the file to .ZIP rather than .EWF
Click here for more information on working with .zip files.