Well, it basically works just like the example you mentioned:
<a href="https://get.adobe.com/flashplayer/" target="_blank">Clique aqui para habilitar o Flash</a>
When clicking, if the default permission is to ask, a message will appear asking if he wants to enable Flash Player .
If the default permission is to block, an icon will appear in the right corner of the browser stating that a plugin has been blocked.
If you are already allowed, you will open the Flash Player site to download the plugin .
You may not be able to reproduce this effect because your default permission is already allowed or blocked. Try switching to the ask permission, then the example will work.