I have one more thing you can try. Please type the following into the Terminal:
brew install libusb
Then try again after restarting the Programmer App.
Also, check in System Information under the Hardware > USB page whether or not the DFU AT32UC3C device shows up when you have the ER-101 hooked up to your Mac in DFU mode like this:
If it shows up here then there is most likely nothing wrong with your ER-101 and it is a software problem on the Mac.