The CDI devices are sold with a PRIVATE LTE APN SIM CARD already installed into the product. This is a private circuit and is already configured. You can optionally buy your own private APN from CDI or you can supply your own SIM cards for the devices. They do require STATIC IP addresses on the LTE side.
You should just connect the antennas , power up the device and it should begin connecting to a tower. As long as you do not have a RED alarm LED it should be connected to the LTE network.
Contact CDI support if you are having problems.