Or MS telling people in a simple way how their sharing works 
But I agree, it has become complicated over the years and Ian’s post covered most of it (Volumio Moderator at the time).
This is what I did to get it working:
- Created the folder with the music to share
- Right-clicked on the folder → Show more options → Properties → Sharing → Share
- Selected “Everybody” and pressed “Add”, close with “Share”, “Done”
- Giving access to “Everybody” is not enough though as Windows 11 forces password protected sharing. Therefore went to Control Panel → Network & Sharing Centre → Change advanced sharing settings
- Opened “All Networks” and disabled “Password-protected sharing”
This completed the windows-side settings.
For Volumio
- Opened the “Sources” menu
- Selected “Add New Drive”
- Entered an Alias
- Added the IP address of my Windows 11 PC
- Entered the name of the folder I shared (not the path, just the name of the folder I right-clicked on!)
- Entered a user and a password (this is MS, it does not matter what you enter, it is not going to be checked)
Done…
Btw. I edited your Topic title to reflect a Windows 11 issue.