My Android device with USB host does not recognize my WiFi Adapter dongle. Is there a way I can install a driver or do anything else? I bought an Android device that doesn't come with WiFi but comes with USB hosts and, as stated in the site, supports Wifi dongles. But mine is not working.

I successfully plugged in a USB mouse, keyboard, hard-drive and a bluetooth dongle but specifically the WiFi dongle doesn't even turn on (the light doesn't turn on).

Is there anything else I can try?
You need to find a WiFi dongle with a chipset the device supports. Each chipset requires different drivers, so you'll have to find one that's supported. There a discussion thread on the site you linked to about exactly this.