Drop the .ovl files inside the folder located here:
Indominus Rex Red Skull:
 C:\Program Files or x86\Epic Games or Steam \JurassicWorldEvolution\Win64\ovldata\Content0\Dinosaurs\IndominusRex

UI:
C:\Program Files or x86 \Epic Games o Steam \JurassicWorldEvolution\Win64\ovldata\Content0\UI\Icons