can't sign in unity3D 5.6.1f1 with error: service not available, please try again later...

I download unity3D 5.6.1(editor 64 bit for

windows) from https://unity3d.com/cn/get-unity/download/archive,andI installed it.
when I sign in , but it shows that service not available, please try again later…

please refer the picture.

Could you help me to solve this problem? Thanks

I have the same problem did you find a solution ?

No solution and no reply after 1 year.

I have the same problem did you find a solution ?