[Basssiiie]

How you include stuff doesn't matter shit, both "" and <> work for every include file. (Although "" allows for files in different directories, but besides that, they're the same.)

For your problem. Go to the download topic and download the plugin as well. Only the include is not enough. Put the plugin in your plugin folder and add "sampp" to your server.cfg after the word 'plugins'. This should remove the errors. Now to get the visible effects in your client, you need to download and install the client files as well.