Double checking, the file you copied to the root of your freshly formatted CF card, it should be named
The Mac download file is named eos7d-v205-mac.dmg, the Windows version is eos7d-v205-win.zip.
Both eos7d-v205-mac.dmg and eos7d-v205-win.zip are compressed files for each platform that must be uncompressed to find the 7D000205.FIR file inside.
The eos7d-v205-mac.dmg file should self extract it's contents, the 7D000205.FIR that the camera needs is a couple levels deep.
I don't use anything Apple, I'm in the “Friends don’t let friends use Apple” camp, so I cannot offer specifics as to how to get to the needed 7D000205.FIR file, but on Windows 7 using 7zip (7zip is an open source Windows file compression and decompression program) I was able to open and find the 7D000205.FIR file inside both the downloaded eos7d-v205-mac.dmg and eos7d-v205-win.zip files.
I imagine that you just double click on the eos7d-v205-mac.dmg file, hopefully you are offered options as to exactly where the eos7d-v205-mac.dmg file should be decompressed so that you can easily find and copy the needed 7D000205.FIR file, then paste it to the root of the CF card.
If, after double clicking eos7d-v205-mac.dmg you cannot easily find the 7D000205.FIR file, there must be a find or search function in Apple's Finder, use that to find 7D000205.FIR, copy, paste and reboot the camera, follow the rest of the instructions.
The 7D000205.FIR file IS the firmware update file. Neither Mac nor Windows has any idea what to do with the .FIR file extension, they need only to be able to copy or move that .FIR file to the root of your CF card where your 7D does indeed know exactly what to do with that file.
Do not simply rename the eos7d-v205-mac.dmg to 7D000205.FIR, that should not work at all.