This is a straightforward process you enter your username, then the Google account password, and if enabled, the two-factor authentication code on top of that. You are asked to sign in to a Google Account after installation. It seems that it is not available for mobile devices yet, as Google is still advertising its Google Photos application for mobile devices on the Photos download page.
The new Google Backup and Sync is available for Windows and Mac operating systems only at this point in time. Downloads are available on Google Drive and Google Photos I could not get the download to start on Google Drive, but the download started fine on Google Photos. The new client replaces the old clients that Google provided for these tasks.
