You will receive an activation code to the email address, which you used to register yourself on kaufmich.com. You can insert the numbers to verify your email address. Your activation code expires after 24 hours, so in case this happens, you will see the following screen:
You should then click on "You didn't receive an email?" Once you click this, you will see your prefilled email address and can check, if this is correct or if you need to change it again. Click "send" and another email with a new verification code will be sent to your registered email address.
Should this also not help, you can contact our support team by giving them your user name and the email address, with which you registered on kaufmich.com.