Your software say your book downloaded successfully but where it is I'm not able to find
If your software says a book downloaded successfully but you can't find it, check the default download location specified by the software or your device's settings, or use your device's file explorer to search for the file with the expected extension.
If you downloaded the book to your computer, open your file explorer (e.g., File Explorer on Windows, Finder on macOS) and navigate to the expected download folder.
Mobile Device:
If you downloaded the book to your phone or tablet, open your file manager app and check the download folder
GOOD luck!!