If the notches are the same as the ones on earlier 25mm hollow spindles, they have to line up with the centre line of the fork leg, so that holes in the spindle align and allow you to pass a screwdriver through to adjust the damping screws in the bottom of the leg. They don't locate on anything physical.
Good luck getting any significant torque on the skinny little spindle nut.
All it does is pull the assembly into place with all the spacers up snug.
I usually nip the rh pinch bolts enough to stop the spindle turning, then draw it up with the spindle nut as tight as possible. Then torque up the LH pinch bolts 1-2-1.
Next slacken the RH pinch bolts and give the forks a good bounce before re-tightening.
Once the pinch bolts are tight you might as well take the spindle nut off as it's doing nothing.
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