I have a Z-603S and had a similar problem. From memory I had to select the baud rate manually. There was also some other option I remember I had to enable in the octoprint settings. Feel free if you want some help via teamviewer to message me. We also have a Z-603S group on facebook, and I've created a forum for JGAurora printers including the Z-603S here: jgauroraforum.com
The forum on thingiverse doesn't work very well, it doesn't notify people which makes it hard to participate.