Welcome to Mobileread.
You have an unusual device, so I fear you won't get loads of specific advice here. I just did a web search and saw pretty much what I suppose you did. One thing I saw that I liked about this device is the price
The fact that your PC doesn't recognize the device is what I would focus on. It should be a new letter drive in Windows Explorer if you have a Windows PC.
If you have another similar cable around the house, try that. And I wouldn't be above rebooting everything, trying a different USB socket, and wiggling the cable a bit. If that doesn't work, I think you need to brave Ematic customer support.