For me something is not working with Unibeast 6. My hack runs fine and I've upgraded to El Capitan directly from AppStore without any problems since I was already using Clover from a long time ago. But I've downloaded Unibeast 6 because I wanted to use it for creating a USB stick for installing El Capitan on a HP laptop. I've used the same USB Drive that I've used before for installing Lion, Mountain Lion an even Yosemite. It's an 8gb SanDisk drive. I've received the famous error "cannot copy files..." that some other users were receiving here, and someone pointed that some drives after the format have less than 7.5gb and that causes the problem, but my drive has 7.65. Tried on all USB ports, all of them USB 2.0. Finally, I give up and buyed a 16gb Verbatim USB drive. But to my surprise, I'm still getting the same error!
El Capitan was downloaded directly from AppStore, and I'm a power user so I know what I'm doing, and obviously I've formated the drive properly. I think that there is some kind of problem when you run this from El Capitan itself instead of running it from Yosemite.
Now I'm making the whole process to create a USB installer with Clover manually...