Raspian comes with VNC server already installed. To use it in Mate i will copy/paste what I answered in another topic:
You need to download the .deb from the webpage:
https://www.realvnc.com/en/connect/download/vnc/raspberrypi/
Then to start it:
https://www.realvnc.com/en/connect/docs/unix-start-stop.html#unix-start-stop