Many of our downloadable products are delivered as zip files (compressed folders containing a variety of materials). Zip files typically require an "unarchiver" utility to decompress the file(s). This is a standard software component included on most modern computers. Therefore, it is recommended that you use a desktop computer initially to "unzip" the files, NOT a mobile device which may not have an unarchiver utility present. Once the zip file has been decompressed into its component files using your desktop PC, these files may then be easily transferred to your other mobile devices.