>>96502224
Sounds like you're getting started with the hobby as a whole. Welcome! Bless your weapons and go!

Something you will find with Citadel whites and off-whites like Rakarth Flesh - especially if they've been in the pot for a while - is that they can get pretty chunky. Make sure you thin them appropriately before you apply them to your model.

In this case, >>96502253 is absolutely right. Warplock Bronze is a a metallic paint, with mica flakes in it to simulate metallic sheen to scale at 28mm. You're meant to paint the "gold" parts of the Castellan model with it like the trim on his armour.

Does the app recommend Agrax Earthshade for this model as well? I suspect it would, intending for you to wash both the Rakarth Flesh on the tabard (same colour on the pauldrons, too, I bet!) and also the metallic parts you paint with the Warplock Bronze.