Problem installing WhatsApp

Hi

I bought a new iPhone (11 Pro) and in many attempts to run the WhatsApp app I encountered difficulties - the app is installed but most of the functions do not work. By clicking on settings for example it takes me out of the app (and in other functions).

In the installation of WhatsApp Business, for example, the app does not load at all.

I contacted WhatsApp customer service and they asked me to do a number of things like reinstalling and resetting the iPhone device. All of these did not help and the problem remained.

I would appreciate your assistance!