Let's take this offline, so i can see how else I can assist. You will likely be using DescPro as this is likely a T series ECU. Possibly a T2 if it is a simple setup or a T6 or T10 due to it being a rally car in need of things such as Anti-Lag and TC.
Please PM your email address and I will help with the next step.
For those following the thread.
The top left is a lemo style connector which many times, as stated in the post, is used for CAN communications. You will typically use a CAN to USB (or PPCAN - Parellel Port Can device to communicate with either DescPro or CalTool)
The bottom left is an autosport connector. This is the more common style download today. Back 16 years ago, this would likely have a different pinout and function than our current download cables.
The other jack correctly stated as an RS232 interface would be an 1/4 phono style plug.
Good day! I am encountering a similar situation. My car is a World Sports Racer and it runs a T2 ecu. When I bought it a few years ago it did not come with software or the RS232 jack to communicate with the ecu. I have run it for a couple of years without issue and without access to the data collected by the ecu.
At our last race we developed a electrical gremlin that we are trying to work out now. Having access to the ecu's data would go a long way to helping us work out the issue. Also it seems these nice little units can be programmed to output the data to my AiM logger but will need to be told to do so through the DESCPRO software.
Any help would be appreciated.