Descarga :
https://ubuntu-mate.org/download/
enlace directo:
https://ubuntu-mate.org/download/
si usas Ubuntu Mate 16.04.2 LTS no olvides actualizar
el entorno Mate de esta Manera:
sudo apt-add-repository ppa:ubuntu-mate-dev/xenial-mate
sudo apt update
sudo apt dist-upgrade
https://launchpad.net/~ubuntu-mate-dev/+archive/ubuntu/xenial-mate