When downloading, updating or syncing apps to an i Device like i Phone 6,i Phone 7 Plus and i Pad Air, apps may occasionally get stuck waiting and never finish installing on the i Phone 6.Even with the latest update on ios 10.3.1, this error would appear sometimes.The length of time will depend on the number of apps you sync to the device. After the update, try and download the apps on i Tunes.
If you have searched for apps on the Safari browser the app install button will redirect you to the App Store, therefore avoid downloading popup apps because they can be malware and various scam. Are you running the latest version 9.2 or an older version?
Also make sure you arn’t using Cellular Data to update(which is very unlikely because of the 100MB limit) for i Phone 7.
Try downloading other Apps If the apps you’re downloading is stuck, try downloading other apps to see if it is stuck too.
The bigger they are, the longer it will take depending on your Wi-Fi Speed.
Updating to the Latest i OS 10.3.1Apple often release new i OS update to fix bugs and glitches.