I have an NTFS drive attached read/write and it works. Copying a large >1gig file from the MBWE to the USB attached drive from my Win Vista computer doesn't work but that looks like it might be a Samba problem. Copying from my Windows machine to the USB attached NTFS drive works as long as the ethernet adaptor on my Windows computer is tweaked. The Linux software used on this device is really old e.g. 2008. There have been lots of Linux changes since 2008!
Can you see the mount point at /proc/mounts? /shares/usb1-1share1 mount point is configured in Samba on my MBWE in /usr/private/user_smb_conf/.overall_share. If the /shares/usb-1-share1 mount point is there, you should be good to go. If not, I think you'll have to figure out how to get the ext3 mounted. I'm guessing that happens in a hotplug script. The easiest path might be to NTFS format the drive?