You can download this specific version without a serial number directly from the Rockwell Automation Product Compatibility and Download Center (PCDC) . in the PCDC search field. Select "RSLinx Classic Lite (free)" from the results.
To download for free, you should use the official Rockwell Automation support site . RSLinx Lite is a free version of the communication software used primarily to support RSLogix and RSNetWorx. Official Download Steps rslinx classic lite 2.59 download free