Downloading tracks and changing to metric measurements

I tried searching for “download tracks” but I got a dialog saying “search terms must contain more than two characters” or something like that,.

To get to the point, I have the Ultimate Edition and when attempting to set up private online races on some tracks and I get a dialog indicating I need to download the track. But where and how?

Also, is it possible to change to metric measurements from the default American ones I hsve?