This may be due to either a poor internet/data connection, or the download timed out because you closed the app/turned off the phone.
Solution: Find a place with a good connection and keep the app open until it finishes downloading completely. If the download stays frozen, please force quit the app, reopen Shaka Guide and try again.
If the download is still stuck or frozen, delete the app, then download it again from the App Store or Play Store, and try again.