Hi, João.
Thank you for contacting the Microsoft community.
As we understand from your post, you have passed Exam MS-102: Microsoft 365 Administrator, but you did not receive the corresponding Certification. We are happy to help!
Please note that Exam MS-102: Microsoft 365 Administrator does not grant a Certification alone, as it is only part of the requirements to achieve the Microsoft 365 Certified: Administrator Expert Certification.
The requirements to earn the Microsoft 365 Certified: Administrator Expert Certification are:
You can review the requirements to earn a Certification by visiting the corresponding Certification page and scrolling down to where it says, "Certification prerequisites" as shown in the image below:

Keep in mind that only one of the Certifications mentioned above is required, so you can choose the one that matches your profile the most. Once all requirements are met, the corresponding Certification will be available on your Learning dashboard within 48 hours.
We hope that this information helps resolve your concern. If so, please let us know by selecting "Yes" where it says, "Did this solve your problem?" located at the lower right corner of this post.
If we do not receive a response, the case will be closed and locked after one business day.
Best regards,