Some questeions what is included ?

[_Aka_]

Hi,
A lot of your questions can be answered by looking at Curvy's WebGL demo. Please take a look at it here: https://curvyeditor.com/demo

Thanks but we tested already folder by folder and that was much at 150 gb project .  same problem also at empty.

I am not aware of any issue happening when opening an empty project having Curvy. Please tell your friend to file a proper bug report (with all the required fields) so I can help him, because I can't help with the little information I have right now.

Why fbx files that are unrelated to Curvery but no ewasy way to find the problem in logs or so ?

Sorry I can't understand this question.

also are there a rain can crash / be derailed ?   and also sounds there for train ?

No, such things are not included in Curvy. You will have to handle your train's physics and sounds.

and can the train tracks / railways snaped to terrain to use at hills and mountains or must the manualy adjusted ?

Yes they can. Please refer to my previous answer for more details: https://forum.curvyeditor.com/thread-597-post-2110.html#pid2110

And can it be used to let Airplanefly in sky along spline like at for example GTA 5 or GTA  and that it look realistic when thy fly curves etc ?

You can move any object along splines, including planes. Please take a look at the demo. If you want something realistic (which GTA is not) you will need to add additional animations to your plane, in plus of the animation done by Curvy.