If you have a MacBook Pro that was made in 2015 or earlier, then you most likely have a combination analog and optical digital output. The easiest way to check is to go to System Profiler -> Audio -> expand Intel High Definition Audio. If SPDIF digital audio output is listed, then you can use a mini TOSLINK to TOSLINK cable to directly connect your Mac to the Emotiva - link.
Otherwise you will need to use a USB-C to Type B cable - link. You’ll also need what’s known as a digital format (or data) converter. This will convert from a USB data stream coming from your Mac into a SPDIF data stream that is sent through an optical digital output to your Emotiva’s optical digital input. A good choice would be the Topping D10s (which can also function as a traditional DAC) - link.