The exception is from hive module and it seems you're trying to create the schema in hive metastore. Please review cluster configurations. UC is supported in DBR 11.1 onwards in single user and shared access modes. Run USE CATALOG command and then execute CREATE DATABASE command.

USE CATALOG <catalog>;

CREATE { DATABASE | SCHEMA } [ IF NOT EXISTS ] <schema_name>

[ MANAGED LOCATION '<location_path>' ]

[ COMMENT <comment> ]

[ WITH DBPROPERTIES ( <property_key = property_value [ , ... ]> ) ];

https://learn.microsoft.com/en-us/azure/databricks/data-governance/unity-catalog/create-schemas