I just ran into this connecting Stripe to Beehiiv. I fixed it by logging into Stripe FIRST to change the automatic setting that would generate an authentication number through a third-party authentication app. Which don't work on a desktop PC. Fortunately, I had downloaded the Stripe backup code when I last logged on using this PC. From there, I was able to get into Stripe and switch it to authenticate using a code sent to my phone. It only took, I think, about 5 authentication codes from various sources before the thing was finally settled. So not easy or quick, but doable.