Make sure that you have installed git. If you don't have installed git yet, try it this way in a console:
sudo apt-get install -y git
After that you should be able to download the sources like this:
git clone https://path/to/repo
That special repo you are linking uses svn so you need to install svn:
sudo apt-get install -y svn
The download works like this:
svn checkout http://android-mt-tutorials.googlecode.com/svn/trunk/ android-mt-tutorials-read-only
By the way it is also explained here:
https://code.google.com/p/android-mt-tutorials/source/checkout