Study Guides require the installation from Google Play Store or Amazon Appstore app - skcTutor (Personal Tutor).  Also checkout the app - skcPublish (Study Guide Creator) if you would like to build your own content and to participate in this Marketplace.

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Optimally you should download directly from Android device into its Download folder.  If you download to a PC, you need to transfer files (through USB connection) with extension PDK or PDZ onto Amazon/Android device into the device's Download folder.