For users running Mac OS Sierra or below who encounter this error like I did, here is exactly what you need to do. to clarify, if your media and update installers fail to install due to "cannot find media to copy", the reason for this is how OSX handles zip files by default, instead of a full unpack, it previews them, meaning large data forks are still locked.
Please follow these instructions to resolve this issue. this is an adaptation from a post but gives clearer support and defined instructions.
1: Download KEKA unzip / zip utility here:
http://www.kekaosx.com/2: Install KEKA and launch.
3: When you have launched KEKA, configure it to run as your default zip / unzip tool so it replaces OSX's default "Archive Utility" migrated from OSX 10.10, now quit the app.
4: Download the media in question. Take careful note that OSX sends the zip files to the trash. Open trash and remove the zip files, move them to the desktop or other location, but delete the folders in the Downloads Folder created from the zip files. these are corrupted.
5: Now select the zip files, right click, open with KEKA. these zip files will be extracted and the new directories created. Once done, you can delete the zip files.
6: As a resource, create a new folder and call it IK MULTIMEDIA, drag the new folders containing the installers and media into this folder. I advise you save this folder containing your kit to an external HDD so you don't suffer this again.
7: Now you can install safely knowing that your files have been FULLY decompressed and not corrupted.
So that you understand how OSX handles compressed files, here's how it works:
Safari as the default browser saves the zip file to the downloads folder, automatically as soon as that file has completed downloading, finder sends an instruction to "Archive Manager" to open the zip file and move the zip file to the trash. The zip file is not fully uncompressed due to the limited nature of the decompression tool. Using KEKA or similar tools like Stuffit, will assist you as long as you set up the zip system to take over from Archive Manager by setting all zip and other archive formats to be handled by the compression / decompression utility of choice.
I hope this guide gives a little better support. I got caught out with this, luckily I was still able to download the media again, monitor the processes and with a little google help and a previous post here that gave a little guidance, this helped fix an issue that worried me. I hope my guide clears a few things up.
All the best.
Ed The Piper.
