Went to activate my sim, but activation site bugs out

During the phone activation process, I encountered a specific issue. When asked about the carrier, my phone indicated 'Searching for Service', which I selected as 'no '. However, instead of proceeding, I was redirected to an error page after seeing the correct page flash onscreen for less then a second. It's worth noting that my device is fully paid off and unlocked. I can even insert the SIM and the carrier boot animation changes to Xfinity Mobile. The problem is that I'm unable to connect to the network or move past this activation step.