Leopard and Office 365 with subscription

Is there anyway to use the download of Office 2011 with the subscription service to Office 365? After I downloaded it to my OS 10.5.8 Mac and launched it for the first time, it said that the subscription service was not allowed in OS 10.5. Without upgrading the OS, can I use Office 365 locally with Office 2011 on my Mac running Leopard?

Thanks,

Mickey