Cannot connect to Databricks SQL Endpoint using PHP and ODBC

Question

I am trying to connect to our Databricks SQL endpoint using PHP in a Docker container.

I setup my Docker container to download and configure the ODBC driver as specified here: https://docs.databricks.com/integrations/bi/jdbc-odbc-bi.html#install-and-configure-the-odbc-driver-for-linux

My Docker setup is at https://github.com/rlorenzo/databricks_php

However, when it try to connect using ODBC from my PHP test script I get the error:

Warning: odbc_connect(): SQL error: [unixODBC][FreeTDS][SQL Server]Unable to connect to data source, SQL state S1000 in SQLConnect in /test_connection.php on line 14
ODBC connect failed: S1000

When I try to connect using the PDO library I get a different error message:

SQLSTATE[08S01] SQLConnect: 20009 [unixODBC][FreeTDS][SQL Server]Unable to connect: Adaptive Server is unavailable or does not exist

The connection details are correct because I was able to connect to the Databricks SQL endpoint using Datagrip. I can also verify that the ODBC library is properly installed because I can query a Microsoft SQL Server.

I must have the Databricks ODBC Connector misconfigured somehow, but I am clueless. From my view everything matches the documentation.

I have tried contacting Databricks support, but they have been unhelpful so far.