https://www.bleepingcomputer.com/news/microsoft/how-to-join-the-windows-insider-program-with-a-local-account/

The Microsoft Windows Insider program allows consumers and professionals to preview the upcoming features of Windows 10 before they are shipped to consumers.

To join the program and install the preview builds, you normally need a Microsoft account and a PC running Windows 10. Unfortunately, you must link your Microsoft account and Windows 10 device to download and install any Insider preview builds.