Adding a drop box pluggin

Hi Ladies and Gentlemen,

Please can anyone assist on how to add a dropbox plugin on my omeka classic.
I downloaded the plugin and unzipped it on the terminal–My problem is I cannot find any documentation on how to install it. Better still, does anyone know an efficient way to upload multiple items in a collection?
My OS is ubuntu , and I’m currently running omeka 2.6.1

Instructions for installing a plugin are here: https://omeka.org/classic/docs/Admin/Adding_and_Managing_Plugins/
Documentation for the Dropbox plugin is at https://omeka.org/classic/docs/Plugins/Dropbox/