When the download does not start, the following may be the cause.
- The download may be restricted depending on the remaining battery. Please plug your device into the power to continue downloading.
- The download is restricted when using "Low Power Mode." Please turn off the "Low Power Mode" and try downloading again.
-
The download may be restricted when many apps are running at the same time. Please close other apps that are running and try downloading again.
- It may take several minutes for the connection to the carrier's network to switch after turning off [Available on Wi-Fi Only] in the "Download Settings". If the download does not start, please try it later.
If these above does not seem to be your case, please refer to this article: Troubleshooting iPhone/iPad/iPod touch.