I can't sign in

Someone is trying to transfer the wifi account to me as I'll be replacing them as the tenant next month. I was told to create an Xfinity account. I tried to create an Xfinity ID and it told me that "This information doesn't match our records". I then went to "Build Your Plan" went through the whole process but didn't pay so that I would gain an account. Now I have an account but the Xfinity website refuses to sign me in. As soon as I sign in it immeadiately logs me back out.