Can't install anything on my iPhone 7 Plus

The operating system on your iPhone 7 plus cannot be updated beyond version 15.8.4. Make sure the software you want to install is compatible with that older version.

Also, make sure your payment method is up to date.

The iPhone 7 Plus originally ran iOS 10. It received five major iOS updates, but cannot run and will never be able to run iOS 16 or higher.

That said, it sounds like your immediate problem is with your account or payment method, and that you must contact Apple to resolve it.

We are not iTunes Store support staff, we are apple users trying to help each other with their devices. You'll need to Contact - Official Apple Support to get into contact with iTunes Store support staff in order to fix this issue

Contact Apple for support & service.

Contact Apple Support – Apple Support (AU)