By securing the – currently version 19.2 from ASUS or the latest stable 18.x branch – you unlock:

Without this driver, your system might fail to recognize its own storage drives, leaving you stuck at the "Where do you want to install Windows?" screen. This guide covers everything from why you need the IRST driver to a step-by-step installation walkthrough. What is the ASUS X515EA IRST Driver?

Click and select the RST folder that you extracted onto your flash drive.