I'd suggest that you start by removing Tableau from the picture. Could you try a couple of things?
1) Try setting up an ODBC connection. Since the MongoDB BI Connector uses the MySQL wire protocol, you'll need to install MySQL drivers if you do not already have them. I use MySQL ODBC 5.3 Unicode Driver.
2) Try connecting to the connector via MySQL Workbench.
Once you've done these, can you report back with your results?