The install scripts setup the gateway software as a service which gets starter achter a reboot. So afterthe installatie( and perhaps a reboot) the gateway should be running.
You can check if it is running by looking at the system log file /var/log/daemon.log. The gateway posts some info here every minute or so.
Remember to use sudo to view this file.
You could also check if the gateway is running by using ps -ef.
If you want to run by hand, don't forget to run the gateway with sudo.
Finally, make sure you have enabled SPI with the programming raspi-config, under Advanced options - SPI.
Good luck.