[Risolto] Can't activate WPML plugins

Background of the issue:
I'm trying to activate some WPML plugins on my WordPress dashboard. The site I need help with is link nascosto.

Symptoms:
I get errors like 'WPML CMS Navigation is enabled but not effective. It requires WPML in order to work.' I also cannot update the plugins: WPML Multilingual CMS, String Translations, Media Translations, and CMS Navigation to their latest version.

Questions:
Can you please help me activate the WPML plugins?
How can I update the WPML plugins to their latest version?