I did not get a blank window. On Android it asked if it is me trying to authenticate so I click Yes. On the phone, as expected, it was no longer asking me to click yes or no because I said yes. On windows MLO, was is still waiting for me to click yes or no on the phone; all I could do is close the window to cancel the attempt to connect to google.
But that was only back then. Today I tried to connect again and this time it just worked, so I don't have any way to know why it did not work that day. When working, the next screen that should have come up was the message that this app is not verified by Google. Today because it did go on to that screen, I was able to verify the connection and finish setup.
Does that make sense, the windows MLO was never being informed that I had clicked Yes on the phone, so I could not do anything further but today it worked so I do not know why it was not working that day. I had started over several times and it still did not work at all.