Cardreader for Music at Mazda 3 2017?

Allegedly, the Mazda 3 has a card reader. It’s about the 2017 model. Can you play from an SD card mp3 or is the card reader only for the Navi? I want to play from a “larger” SD card mp3, e.g. 256GB. Is this possible or does this fail with 20,000 titles when scanning the index?