How can I solve this problem at sign-in?

@JoelYang25 

A screen will pop up asking you to confirm permission on the device you are logging in to. If you allow it there, you will be able to use it on the new device.
If the pop-up does not appear, click "Resubmit" to display the pop-up.
In the past, an email was sent to you, but this seems to have changed recently, so I do not know the details.
However, a little oddly, it showed up even on a logged in device, which puzzled me.