I was able to get a rudimentary anonymous share going by setting the share and filesystem permissions to:
- Everyone (full control)
- Guests (full control)
- ANONYMOUS LOGON (full control)
After that, in the Local Security Policy under Local Policies > Security Options I had to modify
Network access: Shares that can be accessed anonymously
by adding my share to it, like so:
sharename
At that point I was able to get to \\servername\sharename anonymously.