SAMBA4 share confusion

Admittedly, I should be past this point, but I'm not...

Trying to share a directory via SAMBA4 so that a Windows machine can write to it (transferring 700+ GB of email data). I have created the share and marked it as Writable. I've gotten the share to show up when browsing, and I have assigned allowed users via the Webmin SAMBA interface. When I browse to the share it requests my credentials (local UNIX) and then shows me the available shares, but it won't let me browse the shares.

After a bit of man'ing and googling, I have gotten even more confused as there seem to be about 500 different solutions... Any pointers/advice/help?