Is it a real serial port and do you know it works? Unlike USB where the cables just plug and play, with RS-232, there are two "polarities" (DCE and DTE) for the ports and you have to get the cable wired correctly for the situation. Did you see
@WB5UOM comment above about the settings and "password"? The emulation (ANSI, VT100, etc.) should probably not matter unless they were unusually creative in their UI.