Need a cloud. A very big one.
With some kind of organisation feature - especially finding duplicate files.
Security or encryption would be nice if that's even possible but is not essential.
Existing threads https://www.ozbargain.com.au/node/476980 are about places 1tb etc. Definitely not big enough.
(I have many TBs of hard drives all in a mess. I want to put all my stuff in one pile so I can finally get it organised. And then when organised download it all again to local storage in case the cloud blows up. And then possibly/probably keep the cloud (or transfer to another cloud) as a backup in case my house burns down.)
Who can I trust?
G-suite business. Pool together with someone. You can also try the education g-suite pooling trick if you want to save money.
All the features you want are probably best suited as a DIY solution and not related to the cloud service. I wouldn't trust a backup software or solution to do proper encryption and send it to your cloud. That's my personal opinion though.