Hy, I have a btwin inride 300 Classic Trainer and i don’t know what resistance level do i set. Can you help me ?
What kind of trainer choose if I have brown 300?
It seems that decathlon btwin 300 is the sama as RavX TX4 trainer, for which power curve is available here: http://www.powercurvesensor.com/cycling-trainer-power-curves/
Both InRide 300 and TX4 are advertised as 6 resistance level trainers, same number of levels as in the power curve info you shared, but my InRide 300 actually have 7 resistance levels: L 1 2 3 4 5 H. I’m confused. Which one is level 3 and which one is 6? Does the counting start from 0? 
Anyway, TX4 at 3/6 resistance power curve looks almost the same as CycleOps Magneto, which is available on Zwift.
Btwin InRide 100 has been added to Zwift, which is rebranded InRide 300. Use setting 3 on the trainer (L 1 2 3 ) to get accurate power readings.