Welcome to Android Central! It sounds like you downloaded the USB driver from the Acer support website, right? That's for installation onto your Windows computer, in case it's having trouble recognizing your tablet when you plug it in via USB.
You can see if your tablet has a system update available by connecting it to a wi-fi network, then going to the Settings>About Tablet>System Updates menu. Tap Check for Updates, and if one is available, it will prompt you to download and install it. If there is no system update available, then your tablet is likely at the highest version of Android that it will officially get.