For Pi Zero

apt install build-essential git raspberrypi-kernel-headers

For some reason this installs an ARM64 toolchain on a 32-bit Raspberry Pi Zero along with a ton of other stuff that seems unrelated.

git clone https://github.com/HinTak/seeed-voicecard
cd seeed-voicecard
sudo ./install.sh

Installation will take quite some time.

Disable internal sound device and reduce memory consumption.

/boot/config.txt:

# Enable audio (loads snd_bcm2835)
dtparam=audio=off

# Local
gpu_mem=16

Product page

Updated kernel driver