I had similar problem, make a ticket to support about situation. I got another code for registration and this time it worked
Hi @AYBERK AKBALIK,
To resolve this issue, I recommend raising a ticket with Mendix support directly. Please provide them with the details of your registration, including the date you registered and the email address associated with your account. Explain that you haven't received the exam link and that you've already contacted support but haven't received a response.
Mendix support should be able to assist you further by either re-sending the exam link or providing you with the necessary information to access the exam. Keep in mind that the test link is typically valid for one month, so it's important to address this issue promptly.
If you encounter any further issues or delays, don't hesitate to reach out to them again, or explore alternative contact channels such as phone support if available. Good luck with your exam, and I hope the matter gets resolved quickly.