Please follow these steps to install the Tunebang extension and then you'll be able to download mp3s:
2: Locate the downloaded file, tunebang.zip and unzip it to somewhere convenient on your computer
3: Go to the following URL in your browser: chrome://extensions
3: On the chrome://extensions page, check the "Developer mode" checkbox (if it's not already checked)
4: Click on the "Load unpacked extension..." button (scroll up if you can't see it)
5: Select the folder you extracted tunebang.zip to and then click "Ok"
6: You're done. You can now reload the Tunebang website in order to download mp3s