You are likely to rip a protected DVD. Please note that Freemake Video Converter doesn’t rip protected DVD. If you are not sure whether the file protected or not, see this guide http://www.freemake.com/blog/is-my-video-audio-or-dvd-protected-how-can-i-know-it/.
If your DVD isn’t protected, then you can open DVD content, open VIDEO_TS folder and add file called VIDEO_TS.ifo using +Video button in Freemake Video Converter. Besides, don’t forget to read our guide on how to rip DVD with Freemake Video Converter.