The current version is Movie Studio 2025, from where did purchase the 2024 version?
If the activation code begins with P3- then if the error message is:
Error -14, this means that you're putting a valid MAGIX serial number into the wrong MAGIX product or version/edition
Error -24 the serial number has already been registered to another email address - if you have bought the program in 'used' condition then the seller must inform magix that they have sold their copy and to deactivate it, otherwise contact support by email to infoservice@magix.net
If the code you have is a sequence of groups of characters then you have a voucher code which you need to redeem here. You will then be sent an email with the serial number and links to the download.
If none of the above, then post a screenshot of the error message.
First, can you please confirm exactly which Magix software you have purchased? You posted to the Photostory area of the forum but it is not entirely clear that this is your software.
What is the exact wording of the error message you receive, please? A screenshot of it is extremely helpful!
Also, from where did you purchase it? Your mention of 2024 suggests this was NOT direct from Magix since the 2025 version is the current latest available direct from the manufacturer. If you purchased the software from a third-party, especially if it was someone who had previously registered and used it, they must inform Magix directly that they have passed the software to you and so have the serial key de-registered from their account.
Does the serial key you have begin with P3? If not, you most likely have a voucher code. In which case go to this page and follow the advice given there.