Which (e.g., Cinema 4D, Blender, Maya) are you using to generate your renders? What version of After Effects are you currently running?
is a suite of scripts and plugins designed to streamline the handling of UV passes in After Effects. UV passes are special rendering outputs from 3D applications (like Blender, Maya, Cinema 4D) that contain positional data (U and V coordinates) in the red and green channels of an image. AeScripts ft-UVPass Bundle v5.5.1a Download gratis
You mentioned "Download gratis." It is important to clarify the context of this: Which (e