If you're doing it as a business. Stick with distributions that are certified Enterprise-class. (Redhat (Rocky Linux) SUSE, Ubuntu Server, etc) Yes, you can use others, but bleeding edge and un-fully tested distributions can lead to real headaches. This is a business, use a Business class operating system.
As for other software you need. Well, first things first. If you don't know, hire someone who does. Attempting to *wing* creating a cloud storage company will leave you in deep $%^& when something goes south and it WILL go south. Especially if you don't know what you're doing.