It is the download not working - not the BSD subsystem!
There are two possibilities - firstly the server BSD is on is temporarily down which happens from time to time - and if you try it again later it will work.. may be 3 mins or 3 hours - who knows! patience is important.
Or it is possible installer is playing up... go to download it again and this time click on "remove from queue" then refresh sources on installer by clicking the sources icon on the bottom panel and refresh in the top left hand corner.
Once that is done go back and try and download it again and if it works then great. If it doesn't its the server.
This error with file queueing is common and needs to be sorted out by the installer people - its not an error with your phone so don't worry!