Microsoft 365 Apps checks for updates regularly, and they’re downloaded and installed automatically. There aren’t separate downloads for feature, security, or non-security updates. The updates are cumulative, so the most current update includes all the updates that have been previously released for that update channel. While updates are being downloaded, your users can continue to use Office apps. After they’re downloaded, all the available updates for that update channel will install at the same time. If any Office apps are open, your users will be prompted to save their work and close the apps, so that the updates can finish installing.