Zypomorph uses QMK firmware. Documentation on installation, keymaps and compiling can be found here.
If QMK Toolbox doesn't work, try these steps
My fork of QMK can be found here
To install the default keymap:
Download the left/right eeprom files and .hex files here
Right-click each link and "Save link as..." or download the whole repo
Flash the left half
FLIP USB DFU protocol version 1 (doc7618)
Flash: choose your hex file
Use a piece of metal to short the two pads marked RESET
Flash the right half
Place some tweezers/ wire into the holes next to the MASTER jumper. This is needed to activate the USB port, and can be removed after flashing.
Plug in the right half alone, into the unused USB port.
Follow the same steps as the left, but choose
If you're updating the firmware for the right side, make sure RGB is disabled for the slave side.
Remove your jumper wire/tweezers
Plug the leftmost port into your PC, and the two middle ports into each other.
After the initial setup, you can update your keymap using QMK Toolbox, and you only need to flash the master half.
For custom layouts:
Follow these steps
Install and setup QMK and Avrdudess
Edit your keymap as desired and compile hex file
Flash the hex to the master (follow guide above)