WhatsApp won’t work on new device

I’ve recently upgraded my iPhone from a 14 to a 15, but WhatsApp will not work, the app is there it asks for country and telephone number but won’t download, I’ve deleted and reinstalled the app I’ve done all sorts as recommended, I eventually got it on through my old phone as a linked device but once my old phone is returned and WhatsApp is not active on the primary phone it will stop working again from what I have read, it has done the same with both mine and husbands phone both iPhone 15 .. any ideas anyone please ?