Using Whattsup on new iPad without having an iPhone

Is it possible to install and use Whattsup on a new iPad (7th generation) WiFi and cellular. without having to have an iPhone?

i just bought two iPads hoping I can give them to my grandmother and old father. So we could Skype and share photos/videos/chat on Whattsup.

It seems there’s some difficulties as when I’m trying to install Whattsup, it asks for making a photo of a QR with my phone. And it seems it only referring to a computer but not even an iPad.