The Architect credential is an accreditation, not a certification.  Accreditations are less rigorous and less expensive than certifications.  You didn't say which platform you are on, so here are links to the learning plans (which have the exams) for all three platforms.

Azure Databricks Platform Architect Learning Plan (Public) - Databricks Learning

AWS Databricks Platform Architect Learning Plan (Public) - Databricks Learning

GCP Databricks Platform Architect Learning Plan (Public) - Databricks Learning