U can download certificate from the below link
Go to exam result section and click on Get Certificate
If you are talking about SSL certificates, you’d normally get this from whoever issued your SSL certificate.
I use DigiCert and if you do too you can find their certificates here…
Once you have this, if you are hosting on the Mendix Cloud you can add it using the following instructions.
Hope this helps.
if you see the Sign In button then click on it
Then you will see 2 section My registrations and My certificates.
Under My certificates double-click on the certificate you want to download. Then go to Exam result tab and click on GET CERTIFICATE.