Alex had used localhost as the server, but PostgreSQL was on a remote host. Worse, the firewall blocked port 5432. After opening the port and using the correct IP, the connection test succeeded.
Here’s a short, useful story that walks through the practical reality of downloading and setting up the PostgreSQL ODBC driver—something many people assume is trivial, but often isn’t. The Case of the Missing Driver postgres odbc download
Alex searched "PostgreSQL ODBC download" and clicked the first result: a generic postgresql-odbc-16.00.exe . Downloaded, installed, but Tableau kept saying "Driver not found." Alex had used localhost as the server, but