1. Go to the google drive link here to download the livery: 
https://drive.google.com/file/d/1cGc2x8gdDvNk_H16uGjZyc8j0Sn0FLLW/view?usp=drive_link

2. Unzip files in \Saved Games\DCS openbeta\Liveries\AH-64D_BLK_II
If the directory doesn't exist, create one with the same name!