My wife and I arrived in Spain but we're still on the US store. We installed WhatsApp on her iPhone 6 and used it a lot with our workgroup. When the iPhone 6 was damaged, we bought an iPhone 7 and put in her SIM card but my Apple ID. (Apple turned on two-factor without asking and won't let us into her account until we enter the code from the SMS they sent to the broken phone!)
Restored from an iPad backup but the WhatsApp for iPad is not the same app and was not registered to install.
Find the correct one for the iPhone in the store, click "GET" and enter my password. "Ding" "Done" and then the download spinner turns for half a second and says "GET" again. The app is not installed. No pop-ups, messages, or diagnostics of any kind.
Previous phone was 16GB, this one is 32GB and less than half full.
Both had all updates installed promptly.
What is this and what can we do about it?