You can find the driver on the main Rongta support page. Look for the "RLS1100" or "RLS Series" section.
If you have lost the original installation media, contact your Rongta distributor. They can usually provide a new download link. In some countries, resellers also offer free software downloads that allow you to manage multiple scales from a single PC [6†L5-L9]. rongta rls1100 software download link
I'll use the sources I've found to support the information. I'll cite the sources accordingly. I'll also include information about user manuals, driver downloads from Loftware, and the fact that software is included with the scale. I'll also mention that the software might be available from resellers. I'll write the article in English. How to Find and Download the Rongta RLS1100 Software You can find the driver on the main Rongta support page