SparkFun Qwiic RFID-IDXXLA Hookup Guide
Contributors:
Elias The Sparkiest
Elias The Sparkiest 
Hardware Assembly
Simply insert a Qwiic cable between the RedBoard Qwiic and the Qwiic RFID reader. You will also need to solder wire between the Qwiic RedBoard's pin 8 and the Qwiic RFID reader's INT pin. When you are ready, align the headers of the module with the Qwiic RFID reader.
Note: The Qwiic system has a logic level of 3.3V. I have attached the interrupt to pin 8 on the Redboard Qwiic even though the pin is at 5 volts. This will not harm the Qwiic RFID because we're doing a simple digitalRead() but also because the ATTiny84 is tolerant of voltages up to 5.5V.