When you sign into a Google Account during hub set-up, Google will provide you with an authorization code.
Please copy this code to the clipboard by pressing the 'squares' button to the right of the code. Then, if you're on desktop, just close the Google sign-in popup window, or if you're using Safari on mobile, hold down the tab switcher button in the lower-right corner of your screen, then press Close This Tab. You'll now be back at setup.starlinghome.io, where you will find a slot to paste the code. Then, press the CONTINUE button.