Northfield Rewards

My neighbor recommended this app and I was excited to try it out to earn gift cards for my purchases. However, I am stuck in a loop trying to log in. I provide my email address. They send me a link to my inbox. I click it. It takes me to a website, which redirects me to the App Store. I sit there, hoping it will open the Northfield app, but it doesn’t, so I click Open. And then I’m back on the provide your email address form. I’ve done this whole cycle 7 or 8 times now. Super frustrating. I can log into on the website, but no way to enter receipts there. Hope this can be fixed. It looked like a great opportunity.