Is it possible to update macOS without Apple ID?
Yes, there are three ways to update macOS without using an Apple ID. Most important thing to remember is that a user only needs the Mac App Store to download the installer, which downloads the update to the machine. 

You can also download the installer from the Web by visiting this link on Apple Support website. Then copy the installer to the Applications folder. Double click on the application and you will be able to install the update.