J’ai téléchargé Dorico SE 6 (version gratuite) mais je n’ai pas reçu de code d’activation.
Welcome to the forum.
Because this is an english speaking forum you should translate your message, so that everyone can read it.
Regarding your question, how did you get to the download? Did you click on the button on the website for a Dorico SE download?
When going through the website you will be asked for a mail address and that is where the code will be sent to. Have you also checked the spam folder?