For some orders the certificates can be required. If a certificate is required, it is shown in the description of an order as well as in Order Details when you take the order into production.
After you take the order to production and it will appear in My Orders, you can upload certificates needed
Click to add a certificate and upload a scanned copy
As soon as you upload it, the certificates will be displayed here
Certificates are not required for all orders, only for some of them. Information about the need to provide a certificate will always be written in the order description.