Hey Florian,
Actually you do not need the enable pin at all.
I would suggest their use if using the trapezoidal modualtion strategies, but honestly those modulation strategies are not well tested and I would not suggest their use if you’re a beginner, or if you have other option 
SimpleFOC willl not ask you for enable pin and it will use the PWM to modulate the phase voltages, without setting the high-z state.
L298N will work, it is really not the best driver, but it will work.
Here is a thread about it.
https://community.simplefoc.com/t/3-bldc-and-stepper-foc-driver-l298n/296