In 2012, we've written a Synfig Studio guide for animation and installation. At that time, Synfig should be installed from outside Ubuntu repository. Now Synfig is available at Ubuntu official repository. We find Synfig Studio is available starting from Ubuntu 14.04 until 16.04. We can install Synfig studio by performing this command:

sudo apt-get install synfig synfigstudio
Explanation: this will install synfig package with its dependencies and install synfigstudio package which is GUI for synfig. This will download about 10 MB data in Ubuntu 14.04.