There is a video included that walks you through the simple process.
You'll be able to create the interior and some exterior trim molding for just about any project with ease and flexibility. This model is kind of like a kitbash in that it contains 128 of the most common molding, trims and wood millwork used in architectural interiors. It's even possible that you might use the Test Room as your final room by modifying it as needed and saving it. I'm offering it to you in hopes is significantly increases your workflow for interior architectural modeling.