What you are looking at is probably what is known as an external motion controller. Its job is to take instructions from the PC and turn them into the actual signals that the stepper or servo motors need to move the machine. It is defiintely not just a USB to 25-pin adaptor. You are also missing a vital piece in the chain from Vcarve to the machine, which is the control software that runs on the PC and takes the gcode output from Vcarve (a list of "goto such-and-such a position", etc), lets you set machine zero and start position, and all the other "user" things you need to do. It talks to the motion controller that then translates this into something that the stepper drivers can understand.

Widely-used motion controllers include the UC100 which is also USB to 25-pin and the UC300/400 series which are a bit more sophisticated. Also recommended is the UCCNC control software which runs on the PC.

Your posts suggests someone without much experience in this area - lots of people on this forum can help with advice and comments but a bit more info on what you have and where you are coming from would be useful first.