DP32 audio files can be transferred to any computer via the USB or a card reader. The DP32 connected to a PC or Mac will show up as a standard data drive. OS type or version shouldn't be a concern as USB compliance is always a constant.
From the manual:
"Song data and WAVE files can be copied and backed up to a computer connected by USB 2.0."
From Apple's website, the 2015 MacBook Air has 2 USB 3.0 ports (which are 2.0 backward compatible). It also has a SDXC card reader slot so you don't even need the USB connection if you just want to transfer the audio files. You're fine.