There are a few posts here that claim to solve the problem I am having but they do unfortunately not work.
I have managed to install dropbox through the proxy server using the command
sudo https_proxy="http://username:password@your_proxy:proxy_port" dropbox start -i
and Dropbox seemed to download and install properly.
Now however when I want to start dropbox i get the following screen:
Any advice on starting Dropbox through a proxy server?