Vitoriano

If you check the spec from usb 6009, you will see that the analog output have a current draw limit, that is not enough to your fan motor, instead of a relay output, try to use a power mosfet , where the gate will conected to your analog output from 6009, That way you will be enable to control the velocity of the motor using your analog outpout. There is another solution but more complicate, like PWM controls. For initialization will be a good project using the mosfet. Good Luck in the project.