Welcome to the Magix user to user forums, so not a contact for any Magix staff and confidential data, like serial keys, and order numbers should never be posted here. Hence I have edited your post.
Error 14 indicates you are trying to use a serial code for a different product or edition to the one you have installed. You say you bought VDL 2026 Plus. So, which edition does your confirmation email say you have bought? Have you actually installed VDL 2026 Premium or Ultimate rather than Plus? If so, you must uninstall it and then download the VDL 2026 Plus installer and run it to get the correct version of the program.