There are a few reasons why your download may have failed:
- Poor wifi connection. You can only download shows when you're connected to wifi - if the wifi connection is poor, or you lose wifi completely and try to download on 3G/4G, your download will fail.
- Lack of storage on your device. Your device may not have enough room to complete the download, in which case you will need to free up some space on your device.
- Your device may be too slow to handle the download process.