The port number is a default, not a guarantee
When connecting to SAP Business One you enter the Service Layer address. Common installations use port 50000, but that is a default — yours may differ. Getting the address from your system administrator rather than guessing removes the biggest time sink in the setup.
The company database name is asked for separately. You see it on the SAP Business One client's login screen; on installations running several companies, this field decides which one you connect to.