The issue here is that the main user using which you login to Azure Portal does not have the Databricks Account Admin role. It has Global Admin role though.

By default Azure creates an external user for you which has the Databricks Account Admin role. Follow these steps:

1. Login to your Azure portal.
2. Navigate to Microsoft Entra Id -> Manage -> All users Here you will see a user having EXT in the name. That is the default external user for you.

3. Copy this username.
4. Logout from portal.
5. Open Azure Portal in a new Window.
6. Login to Azure portal again but this time using the external user you copied.
7. It will tell you that the password is incorrect.
8. Click on reset password.
9. Once the password is reset, login to Azure portal with the EXT user and the new password.
10. Navigate to Databricks service. Launch the workspace.
11. In the same browser window open a new tab and open the following URL: accounts.azuredatabricks.net

12. Click on Continue with Mircosoft Entra Id
13. Once in you can start creating the Metastore for Unity Catalog, etc.