Pls help-when proving ground instincts unlocks

I am level 36 .

When I am able to unlock PROVING GROUND INSTINTS ??

On Eden Map where I activated it with my first level 50 character it is not possible … the activation button on the stone is inactive.

What special mission or level to reach or any stuff to do… in order to activate it ?

Complete the story on normal mode, then theyre active (AFAIK)

Ah ok… ty