@buseca
Upon activation of the plugin, you get a new tab in the network blog settings page. Go to your blog list and ‘edit’ one of them, you should see the tab now.
To properly use the plugin, you need to assign a language to each one of your blogs, in order to be able to interlink them.
The fact that you cannot see the plugin in your blogs’ plugins page is due to the fact that you “network enabled” it. This is a WP feature and has nothing to do with the plugin itself.
If you have any further questions, feel free to post them here.
Inpsyde Team