Trying to achieve paint drip effect on a black background. I't not working (Included File source)

I got a bunch of things going. I followed along with this tutorial....

https://www.youtube.com/watch?v=2VU88ot_HJE&ab_channel=PhotoshopTutorials-PSt

Ok So I'm trying to make paint drips I thought darken cuts it out. I think since clipping mask got used it's messing up, can't do it. Sitting for 3 hours now

Either I forgot or I'm dumb. It suppose to invert that selection and have the drips from the paint.

Yes I'm trying to manipulate a smart object itself as to put n a product/software box. 

What is not computing?