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Please follow the below Microsoft document for these details.
Account name: The full account name of your Snowflake account (including additional segments that identify the region and cloud platform), e.g. xy12345.east-us-2.azure.
User name: The login name of the user for the connection.
Regarding the error message:
Per the error message, login URL failed with a HTTP error code 403, which means that the request was forbidden. This could be due to incorrect account name or username.
I hope this helps. Please let me know if you have any further questions.