how to get ARMv8 model

I'm trying to run example of ds-5 for armv8.

on this step, I can't find FVP_VE_Cortex-A57x4.so, could anyone tell me how to get ARMv8 model? and what's it? how to install it?

thanks very much

"On Linux hosts: ./model_shell <Install dir of ARMv8 model>/lib/FVP_VE_Cortex-A57x4.so -S"