Wood laminate floor preparation

I ready to install wood laminate flooring onto existing wood flooring an have an few questions about preping the floor. The existing floor was old, smelled of years of pet urine. The floor is not salvageable. I scrubbed the floor to rid of the pungent smell and rid of the years of dirt/grim.

I hired someone to paint the floor (GASP!) with an oil based Killz primer to rid of the smell further. But, the person hired didn't remove the carpet tack strips, left over nails, drywall plaster, etc and painted right over it. They're a few wood planks that I will need to replace because they squeak and/or not nailed down.

How clean (debris free) must the floor be before installation of the vapor barrier, and wood laminate flooring. I'm installing an 8mm thick, 5" wide laminate planks that has padding attached to the bottom.

Does the floor have to be 100% debris free?

Any tips or comments welcome.

Carpeted floors with years of uncleaned pet stain. Dirtiest carpet ever.

Before oil based primer In this picture you can see how dirty the floor was before being scrubbed (top). The light brown is after the floor being scrubbed.

After oil based primer if you zoom in, you can see how bad shape the floor was.