@HKAN-SDERLUND Long time since i looked but don't think you get a code, when you open the program is there an option to use in Trial mode when it asks for activation code?
The trial code should begin with TRIALC- followed by a sequence of number groups separated by hyphens ( - ) you need to copy the whole code including the TRIALC- and paste it into the activation dialog in the program.
Is the coupon for something else - it is not usual to receive a coupon for the trial version, however they can be redeemed here to get the serial number, login with the email address you will receive this by email - do check your spam folder if you think you have not got the email for some reason emails from Magix occasionally end up there.
Please note the forum is a user to user forum, not Magix Support