1. Download APK first, then copy to your Android device's SD card

2. Install APK, DO NOT open app

3. Download obb files, then rename to 'main.1.1000000238419.com.zinggames.zombierollerz.obb'

4. Copy obb file to /SDCARD/Android/obb/com.zinggames.zombierollerz/main.1.1000000238419.com.zinggames.zombierollerz.obb