how am I supposed to upgrade since there is no Norton 360 to upgrade?

I already upgraded my OS to Win 10 which means I could not install my Norton 360 from my previous Win 7.  So without having Norton 360 on my machine, how am I supposed to upgrade since there is no Norton 360 to upgrade.  When or how can I download and install a Win 10 compatible Norton 360?  (NortonN360Downloader installs (or fails to install) the previous version.)  Thanks...