: Ensure you have all the related files in the same folder. You must have RTS0003.7z.001 at a minimum. If there are more, they will follow the pattern .003 , .004 , etc..
The file extension indicates that you have the second part of a split compressed archive. To "put it together," you need to combine it with its matching first part (and any subsequent parts) to extract the original content. RTS0003.7z.002
The software will automatically detect and "stitch" part .002 (and all others) together to reconstruct the original file. Troubleshooting : Ensure you have all the related files in the same folder