Hi Javier,
The river 5 plugin I use is one I made myself. It is pretty simple, but should be used with the caveat that I am a primary school teacher, not a developer.

If you want to use it:
Download from github: https://github.com/troutcolor/wp-river5
Upload the folder to your blogs plugin folder via ftp or sftp
Activate the plugin
Use the short code to point to your river on a page.

Does that help?