According to the OfflineInsiderEnroll Github project page;
Join Windows Insider Program without a Microsoft Account
OfflineInsiderEnroll is a simple script to join the Windows Insider Program on the machine it is executed on using a local account. It is still necessary to set the Telemetry setting of the system to Full as this is a requirement for receiving Windows Insider builds. To join the Windows Insider Program using the OfflineInsiderEnroll script, follow the instructions outlined below.
Download the latest version of the script from the project’s GitHub website. You can check the source in any plain text editor, e.g. Notepad before you run the script.Right-click on the script with the .cmd file extension and select Run as administrator to run it with elevated rights – otherwise, you’ll get an error message stating that the operation requires elevation.The script displays the available Windows Insider Program channels that you may change. Select one of the channels by pressing the corresponding letter and then hit the Enter key.If the machine never joined an Insider program before, you are asked to restart the computer to enable Microsoft Flight Signing – this is another requirement for joining the Insider program on the machine.Insider builds are offered via Windows Update after the process completes.
That’s it! Read: How to check if you are Flighting Insider Builds.
