WhatsApp web linking issue on iPad

I had a whatsapp app on my ipad which I tried to delete and reinstall as there seemed to be a glitch although it had been working for over a year. I was unable to reinstall as it said no longer compatible so I went to Whatsapp web which I already had on my pc. That works but every time I open either I have to scan the qr code to link device again?

[Re-Titled by Moderator]