Hey @Christina! Apologies for the inconvenience. Looks like you got a CDMA SIM card, so you would need to activate your phone/plan through this link. You will be asked for your billing/to pick a plan again, but don't worry, you won't actually be billed again! As long as you pick the plan you already paid for, it will simply pull from your account balance to activate the plan.
If you're still experiencing issues, you can find our live chat support on the bottom right-hand side of this page between 10am-5:30pm EST