Allyoving Said:
"Installing what’s app on iPhone 5s: My iPhone 6s has died so using an old 5s but it won’t install what’s app. I get stuck in a loop of installing and then just terms & conditions, it won’t open. I have IOS 12.5.7."
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If an App Install Is in a Loop:
A. Close All Apps:
These Apps may be open. So, save what need be, and then close all apps. Hold you finger down as you swipe up form the bottom-left corner of your screen. Then, close all of these open apps, by sweeping up quickly for all apps.
B. Start with a Restart:
Restart your iPhone: Restart your iPhone - Apple Support
C. Reinstall WhatsApp:
Uninstall WhatsApp and then install it once more. Click on iOS, on this link: How to download or uninstall WhatsApp - WhatsApp
D. Meet System Requirements:
See the All requirements are met, as of this reply: How to download or uninstall WhatsApp - WhatsApp