Snap Camera is in the main Raspian Repositories. Install it with:
$ sudo apt-get install python3-snap-camera
You must also enable the camera with:
$ sudo raspi-config
And also uncomment hdmi_force_hotplug=1 in /boot/config.txt.
You start Snap Camera by running:
$ snap-camera
Snap Camera also runs as a service. To start Snap Camera:
$ sudo service snap-camera start
To stop Snap Camera:
$ sudo service snap-camera stop
To enable Snap Camera to run at boot:
$ sudo update-rc.d snap-camera defaults