This is what the Microsoft system requirements page for Windows 11 says
Windows 11 Pro for personal use and Windows 11 Home require internet connectivity and a Microsoft account during initial device set-up.
https://www.microsoft.com/en-gb/windows/windows-11-specifications
I guess you were building machines with a Windows Enterprise license. This would explain why you had the option to setup an offline account.
Steps to setup a local account on Windows 11 Home https://www.tomshardware.com/how-to/install-windows-11-without-microsoft-account
https://en.wikipedia.org/wiki/Samba_(software) I just searched for the "samba computer" and this was the first link.
See if you can find some introductory videos that are suitable for you on YouVideo or elsewhere that are suitable for you to work out if you are ready to set up your first home server.
If you just need some storage you could just get a "cheap" USB storage spinning rust external hard drive and move the data that you don't need day to day onto the drive. At a later date you get a Raspberry Pi or second hand small PC and use the PC as a server with the same drive attached.