I’m sorry but we have not started supporting Mac OS 10.11 El Capitan yet: http://www.steinberg.net/en/newsandevents/news/newsdetail/article/important-information-regarding-os-x-1011-3359.html
My best suggestion would be to use Mac OS 10.9 Mavericks or 10.10 Yosemite for the time being. That said, if you encounter an issue on Mac OS 10.9 Mavericks / 10.10 Yosemite, then please submit a support request in your MySteinberg account.
Thank you.