Hi @Indika Debnath​ 

First of all congratulations on your completion, glad you are learning about databricks.If you completed all the steps mentioned to receive the certification voucher within the mentioned timeline, you will be receiving the same, also for any issue with Academy learning/certifications, you can raise a ticket in the below link, and sharing it with you for your future reference as well.

https://help.databricks.com/s/contact-us?ReqType=training

Happy Learning!!