Also Windows: "Ask your network administrator for access."
Me: "Well I'm my own network administrator so what questions do you want me to ask myself"?
Windows: "Enter network username and password."
Me: There is no network username or password. Sod it, I'll bung them on an external disk.
That's a security quirk. Microsoft reeeeeally doesn't want you to do anonymous SMB anymore, and with every version of Windows, Microsoft has made is more complicated to get it working like that. It's probably still possible, but easier just to make a quick local user account and assign it read/write permissions to the share. Samba on Linux can still do it without as much fuss, but I've long since just accepted the extra step.