ZBrushCentral

Impossible to make the UV (for realistic noise)

Good morning

I need to add some grain to the model, I use “Noise Maker” but to avoid the stretching effect I think if there is a UV it will be ok?
So I used UVmaster > disable simmetry > work on cloning > unpack… but it crashes every time.
How to solve this? How to achieve my goal?

(the link of the 3d moel below)