I can’t either. It seems the site/server has something issues or this happens because we are not using Samsung device.
Galaxy watch 46mm
Huawei P30 pro
As I expected the problem with signing in using android device other than samsung. I tried connecting same watch to old Samsung S6 edge and it worked fine after updating the old device firmware and found no issue in signing in to Samsung account.
But this is really disappointment as I want to use it with the new android device other than Samsung.
samsung must do something.