Activated SIM, but can't login or use phone

I ordered a new SIM card for my phone number that I want to port in from Boost Mobile, and I selected a prepaid plan for my unlocked iPhone 6s. When I tried to activate the SIM card online, it said that the card had already been activated and showed that the number associated with it is the one I want to port in. It said to login to manage my account, but when I tried to, it said my information was invalid. I tried to change my password, but it still said my info was invalid. I checked the status of my number transfer/port on AT&T's website, and it said that my port has been confirmed by my previous provider.

Also, my phone accepted the new SIM card and shows four bars of service, but I cannot make calls, send texts, or use data.