I purchased a realtek rtl881au for y desktop that doesn't have wifi. It connects to the network, but says no internet access, is this because my desktop doesn't have integrated wifi?
No, it is a wireless card / adapter in itself, try uninstalling the driver and re-installing it.
Have you connected to your network properly, ie entered the network password etc ?
Sometimes my network plays up the same, and the way around it is to shut down the computer, then remove power from the router, leave for about 30 seconds, then power on the router, wait until its fully booted up, ie all light on it are on, then start up the computer and allow it to re-connect.