DDLC as in... doki doki literature club? You can check your browser's downloads section to see if the file actually downloaded, and where it is. From there you should be able to extract it.
Ok, ignore that page for now its basically the same instructions but for a different game (provided as a reference). Were you able to successfully copy the files to the linux files folder, and are you able to open the terminal program?
If you are unable to right click, you can also try pushing the ALT key while left clicking.