May be a simple question...Do you use the USB ports on the backside of the iMac ...
Edit: I also like to add this url with some more info..
http://photofocus.com/2015/10/02/canon-eos-utility-vs-macs-new-os-el-capitan/
I failed to specify before my computer, which is a Macbook Pro from early 2013, and not an iMac. I've tried both USB ports, to no success. I've read the article you so kindly added to the post, but unfortunately, it seems everything worked correctly for the writer, which is not the case for me. There is no communication between my laptop and my camera. The software opens, but the options to DOWNLOAD IMAGES or REMOTE SHOOTING (which is the one I need to upload the Picture Style), are not available because the camera is not detected.
(BTW, I want to apologise for my grammar and syntax, english is not my first language.