The default Windows filesharing mechanism is SMB. That's what a Windows fileshare client expects: a SMB share which supports Windows domain authentication. It doesn't matter what the OS controlling or hosting the the share. It can be Linux, Windows, MAC, etc, as long as the sharing mechanism is SMB and it provides Windows authentication so your domain clients are authenticated transparently.
If your NAS can produce SMB shares and supports Windows authentication its should work transparently for BPC.