You just bought the LCR -
help me with the terminology since we don't see SEATs on this side of the pond. You bought a Leon Cupra - correct? Is it brand new? 2006 or newer? If so, you have no option but to buy the genuine Ross-Tech dongle style intelligent interface. Why? The new Leons use CAN diagnostics which can only be supported with our current generation software and interfaces. The shareware versions of the program will not work with the CAN based cars as these versions were released prior to the cars being released (2003 and 2004).
If it is older than 2006, you should be able to use the dumb aftermarket leads and the shareware version of the software. The "dumb" leads do not have built in computer smarts. Hence the reason they are significantly cheaper.
Hope that helps with the interface being intelligent vs dumb.