Hi, I have the same problem. I bought a new laptop and I cannot use it because it is not allowing me to login. The Windows it came with is Windows 8. I tried to use the link you have provided to upgrade to Windows 10, however there is not enough disc space (considering the laptop is brand new, I don't think this is an option for me).
Please, could you advise me on how to solve the problem. I cannot use my new laptop and I need it for uni, which is why I bought it initially.