Guys I've been trying to download this plugin for bootstrap. It's called Growl. The link doesn't give the instruction how to download it. Also I tried running the code without the plugin because maybe this is already built-in in the bootstrap but no. It isn't. There are other Growl plugins too but I like this one.
You can click on the GitHub icon on the plugin's page which will take you to their GitHub page. There you can download it from dist folder.