I have same problems during the installation with armbian-config. Anyway I have downloaded the kernel source, Renegade option in compile.sh, and Im using insmod and the 8821cu.ko is loaded. But the kernel freeze with nulla pointer in rtw_os_ndev_register. May Be there Is a bug in halmac routines. Iam already using the driver on x86 Ubuntu 1604 and It works well. Im using old version 4.4.154 on rk3228