Will this desktop setup work with the iMac running 10.11.6?
It "should" work. From the technical specifications page:
Requires a PC that meets the requirements for and has installed one of these operating systems:
- Windows 10 / 8 / 7
- Mac OS X v10.4 – 10.7
It's just an USB HID (Human Interface Device). Now, there may be certain keyboard/mouse functions that are not available due to the limited availability.