Unidays verification loops on UK Apple Store

I go into the Unidays app and get the Apple offer, I’m redirected to US apple store when I need the UK apple store so I manually change the url. I go through the motions and go to checkout. It says I need to verify my Unidays account so I do it, put in the code from my email and everything and then it asks me to sign into icloud. I do, page is loading and it takes me right back to the bag page. I checkout again, it asks me to verify, I click but this time it skips the code sending and goes straight to sign into icloud to bag again and it keeps doing this. Does anyone know what the problem is?

[Re-Titled by Moderator]