Форуми / Cotonti / Extensions / [Plugin] Cotonti Social

The plugin is not a standalone one, so it's not like you can open it in 1 click. It hooks into other modules.

You will have to modify the users.details.tpl file and include the necessary tags to add the Cot Social features.
I think Dylon included a demo version, so you could try moving those files into your theme folder to get started.
See which tags are being used and what they do.

Hope that helps.