system
6
You have to install before activation. You can use a Avast! Free, or a free trial of paid version before pulling the trigger on a purchase. Either way, if you choose a paid version, you just insert the license file into the Avast! UI that comes via email after the financial business is done. That will either activate the trial for the duration of the license, or upgrade Avast! free to your paid version of choice. Since you are having problems, I would take the trial for a spin, myself.