There is a Debian image available with instructions to install on eMMC at https://wiki.friendlyelec.com/wiki/index.php/CM3588#Install_OS Is there any specific reason you'd rather use ARMbian rather than that Debian install? You may be able to replace the OS files in the provided image so the install...

@yaazzz do you think it would be possible to control the fan speed by altering the voltage that the fan port sends out? By default it outputs 5V for 100% fan speed but I'd like to be able to adjust to 4 or 4.5V to slow down the fans and reduce noise.

This solution worked great on my CM3588 NAS kit. Thank you both for your contribution!