Sign in with your username and password.
Enter the 6-digit code from your authenticator app.
Two-factor sign-in is required. Scan this code with your authenticator app (Passwords on Mac/iPhone, 1Password, Google Authenticator), or type the key by hand. Then enter the 6-digit code it shows.
Save these recovery codes now. Each works once if you lose your phone. They will not be shown again.