backing up to norton cloud
I have Norton 360 with 250G of cloud space but I can't get my MacBook to back up to it. Norton says that it is apple who doesn't allow 3rd party back up services. However, on the "official" apple support page under back ups it says you can set Time Machine to back up to a portable drive (USB) or a 3rd party cloud service.
Which statement above is accurate? Norton's or Apple's? If Apple's site is correct, how do I get Time Machine to do a weekly update to my Norton 360 cloud space?
MacBook Pro 13", macOS 10.12