MacBook Air (Early 2015) Network Driver for Linux
There is no such thing as a late 2015 MacBook Air model. I'm assuming you have the early 2015 model.

In that case your computer has a Broadcom BCM4360 chipset for WiFi.

The driver you would need in debian is the "wl" driver. You will probably need to install the broadcom-sta-dkms package manually and then load the wl driver.

The driver is non-free/binary-only so probably not listed during installation.