That looks as if it might be an American site? The phone numbers are not UK codes. Anyway, it's lying. I couldn't get a Blink guest code because as soon as I typed anything into the required field for my phone number it told me that this was an invalid number. I literally tried every digit from 0 to 9 and got the same result.
There is a "Customer Support" phone number on the charger outside my friend's house, 0330 111 0076, but do I trust them to answer? I do not.
I'll take my granny charger so I can charge at my friend's house itself, but that charger 50 yards away would be really handy if I could access it. Having doubts here.