I'm no expert, but I have made pollo ala brasa for actual Peruvians, and they gave me props. And I have a TON of respect for Serious Eats and especially Kenji Lopez-Alt, but this recipe makes no sense to me.
Gummi is right, IMO this requires some sourcing of aji amarillo paste, huacatay, etc.. The good news is that if you can't find it in your area, Amazon can help you out. Also the sauces (one that's mayo based, and another that's basically jalepenos and lime juice) are a huge addition to the final flavors of this. I've gotten good results by washing the chickens first in lemon water, then marinating them overnight in your aji and huacatay and etc..
And I know they are hard to come by, but this is WAY better with a rotisserie.