SharePoint - File Server
Set up a 1TB storage file server limit per user license, where OneDrive for Business is used as a backup tool to access these files in Windows.
Files can also be accessed online through the SharePoint portal.
SharePoint Online Working as a File Server
Set security permissions for folders and files within SharePoint Online document libraries, and keep your company's confidential information safe. Invite people from outside the organization to join your team site, and guests will have the level of access you set (to join SharePoint Online, users need to have a Microsoft account).