If something takes off it becomes a successful product or a fashion. It was in demand = everyone wanted it.

Prior to Windows, computers were cumbersome to use and required a working knowledge of the DOS operating system, setting aside Apple. Therefore computers were used by hobbyists and professionals only. With Windows using a computer became much easier and more intuitive. So what "took off" was the sale of personal computers to the home and business.

https://dictionary.cambridge.org/us/dictionary/english/take-off become popular and successful.... I don't know what the things are in this sentence. However, it seems to say that their success depended heavily on Microsoft Windows. If there were no Microsoft Windows, it would have failed.