Download the latest zip file from https://github.com/mrdeadguy34/deemix-chrome-extension/releases/ Unzip the file to a local directory. Go to chrome://extensions and click load unpacked and point to the unzipped file. All done!
To download your songs just visit https://deezer.com/us/ and you should see a download button on any album or playlist.
To host your own server used to download the files visit: https://github.com/mrdeadguy34/deemix-dl-django-server Then point then edit the content.js file to point the DL_URL to the server's ip.