To setup Google Single Sign On, log in to your Backup Radar account first and under Configuration>Tenant Settings, decide whether you want to lock down your logins to only Google Sign on accounts. To lock it down to a specific domain you can turn on Google enforcement for login and setup the domain(s) you plan to allow.
Under Configuration, click on Profile.
Under Authorization, link your Google account.
Once you do this you will be prompted to login with your google Account:
You should then see a confirmation it has been linked: