Understand datasheet current transformer
This is made for measuring the current. It can be used in switch mode power supplies or in other high frequency circuits 50 kHz...1 MHz. It has no use in audio or normal mains power frequencies. The primary coil is in series with the circuit whose current you are measuring. The secondary coil must have a load resistance. You connect the voltage measuring device in parallel with the load resistor.

The given equations are for preventing the saturation of the ferrite core and for calculating the load resistor for the wanted conversion ratio from Amperes in the primary to Volts in the output.

Leaving the load resistor off gives a high output voltage. It can be disastrous for the insulation and the connected voltage measuring circuits.

The voltage-time product is one simple way to characterize how long pulses with a given voltage can be applied before the unwanted transversal current (=an useless part of the current in transformers) grows too high. I believe that the voltage to be used here is the output voltage.

Addendum due the comments: This definitely is an ordinary transformer in terms of the transformer theory, but it has only 1 turn in the primary coil. Let's assume you have the 100 turns in secondary -model. Its secondary inductance is 2mH. The primary inductance is only 0,2uH. If you connect 5V to it, the unwanted transversal current grows at rate (5V/0,2uH) = 25A/us. If your Arduino could supply say 25mA, it takes 1 nanosecond before the used output is shorted. You have no way to generate say 100 picosecond pulses. And if you had it, it's still useless because the frequency range of the transformer ends to 1 megahetz and you needed say 10GHz. 

If you need high voltage pulses, get a transformer that is designed for it.

You may arque, that I just wrote that the secondary voltage can grow harmfully high without a proper loading resistor. But this is in applications where the primary current is amperes and in any case there's other stuff in series to keep the primary current reasonable. The one turn primary alone is a short circuit and it should be, because otherwise it would remarkably disturb the measured current.