If you are on a Macbook Pro 15", it has a direct spdif input. Optical only. So check your Mac manual
13" MB Pro has only output. Most other Macs have optical in and output. You will need an odd Apple cable, from 3,5 mm jack to optical spdif. These are 3$ or so, unless you buy from Apple, of course.
Or tell us which Mac you use exactly, like "a mid 2010 iMac 27".
And yes, that Amazon link changed in between. Lemme see if I can find a spdif to USB input on a more reputable site
There's at least the MiniDSP one, which doubles as ADAT interface, so it can do eight channels too.
https://www.minidsp.com/products/usb-au ... reamer-box
This one is the best one I know (sturdy build, good support etc.), but it is 105$...
Internal optical on your Mac is 'free', and the exact same quality.