Dear Luigi,
I apologize for the “disinformation” last time, the theme uses the Grunion contact form base, and it does not play well with Contact Form 7, since they are using the same shortcode (see e.g. this thread on WP forums). Please try disabling contact form 7, and the theme’s form will function as intended.
In case you’re missing some other information from the theme manual, please let me know!
Sincerely,
Andrii / Satori Studio