The voltage of your cnc power supply should be greater than or equal to the rated voltage of your stepper motor. Otherwise, the motor will not receive its full rated current and you will not get the full performance that the motor is capable of. It is OK for the power supply voltage to be higher than the rated voltage of the motor because the Tic has active current limiting. (It rapidly switches the power to the motor on and off while measuring the current to make sure it does not go too high.)
A higher power supply voltage is usually desirable since it allows higher speed and torque. However, if the power supply voltage is extremely high compared to the stepper motor’s rated voltage and you want to use microstepping, you might experience skipped steps.
The voltage of your power supply should be within the operating voltage range of the Tic. Otherwise, the Tic could malfunction or (in the case of high voltages) be damaged.
The continuous current per phase of the Tic should be greater than or equal to the rated current of the stepper motor. Otherwise, the Tic will not be able to deliver the full rated current to the motor and you will not get the full performance that your motor is capable of.
We generally recommend you choose a power supply with a current limit that is at least at least twice the current limit you are planning to use on the Tic as that amount of current should always be safely beyond what the Tic will draw. The current limit you configure on the Tic should generally not exceed the stepper motor’s rated current and should not exceed the continuous current per phase of the Tic.
It is worth noting again that since the Tic actively limits current through the motor coils, you can safely use power supplies with voltages above the rated voltage of the stepper motor as long as you set the current limit to not exceed the best stepper motor’s rated current.