To obtain a board for your kit you can find it on avnet.com Search for part number: AES-PMOD-SENSOR1-SIL-G The cost of the board is currently $10.
You will also need to obtain some jumper wires to connect it to the celluar shield's PMOD connector. Please carefully read the kit's Getting Started Guide pdf where it outlines how to wire it, some wires need to be crossed.
Best Regards