Hope you don't mind us replying in English. You don't need a code to join a Family subscription. If the owner invited you, you should receive a mail. From there:
Open the mail and clickACCEPT INVITATION. You're redirected to your account page, where you'll see a confirmation screen. Note:If you're not already logged in or don't have an account yet, you'll be asked to log in or sign up before seeing the confirmation.
Enter your details and clickSUBMITto join the Premium for Family plan.
We suggest that you check out this help article for more info about Premium for Family.