Because Teams' file storage is provided by SharePoint, you have all of SharePoint's features available- specifically the Restricted View permission level to prevent team members from downloading or otherwise copying files.
Office 365 is a line of subscription services offered by Microsoft as part of the Microsoft Office product line. The brand encompasses subscription plans that allow use of the Microsoft Office software suite over the life of the subscription, as well as cloud-based software as a service products for business environments, such as hosted Exchange Server and SharePoint Server. All Office 365 plans include automatic updates to their respective software applications at no additional charge, as opposed to conventional licenses for these programs where new versions require purchase of a new license.