The middle of the dialog holds one sign-in method at a time; the rest sit in the or continue with row along the bottom, and one click swaps them in. There are three: phone (the one you start on), email and Google.
Signing in with a code: enter your phone number or email, hit Send code, type in the six digits you get, then hit Sign in or sign up.
- The code is 6 digits and good for 5 minutes.
- One code a minute per address, which is why the button turns into "Resend in 60s" after you use it, and ten a day at most.
- Typed the code wrong? Just retype it — no need to send a new one.
- An account that doesn't exist yet is created for you, so there's nowhere you have to go and sign up first.
- For phone, use + country code + number (for example, +14155550123). Mainland China numbers can use +86 or the 11-digit local form. Email and Google have no country restriction.
Google: click that tile and a small window opens on Google's consent page; pick your account there and this page signs itself in — the tile spins while it waits. If no window appeared (your browser most likely blocked it), click the tile again. Some deployments have no Google credentials configured, and then the tile isn't there at all.
In the desktop app this screen fills the whole window and can't be closed: nothing in the app works until you're in. What it offers is Open browser — click it and a confirmation page opens in your system browser; check that the code on that page matches the one shown in the app, hit approve, and the app signs itself in (if the browser didn't come up, use Did it not open automatically? Click here to try again). To use a code instead, click email in the bottom row; the Browser tile there takes you back. There is no Google tile in the desktop app.