Lately when I forced to login to FaceBook they will sent a WhatsApp message to my phone number, even though I don’t use WhatsApp. I’d like to see if there is really an account with my number. I tried going to the web client but it seems to be requiring to pair with a device app.
The person who had your number previously used WhatsApp. Maybe they are still using that number for WhatsApp.
Without regular access to the phone number, WhatsApp will not work. I know it’s a couple months (from long term travel), but not longer. I set up an account for the landline at work, but it fails every few months and has to be re-established