The simplest way to attach the sensor is to use this STEMMA cable. No soldering required! Just plug it right in to the port on either side.
I didn't have a double-ended STEMMA cable on hand during the build, so I used a slightly different method using this STEMMA-to-male-header pin cable. The benefit of this was that the female header on the sensor creates a really stable way to attach the sensor in a perpendicular orientation by the money slit.
Solder your female header onto the bottom side of the sensor. Plug in the four cables into the first four header ports as shown: red to VIN, black to G, yellow to SCL, and blue to SDA.
If you're new to headers, you can check out this guide for some tips.
Plug the other end into your MatrixPortal and you're ready to go.