Per the website, it looks like it has to be painted/stained and assembled.
"Once assembled, our Stockpen/Corral kit measures approximately 23″ x 10 1/2″ and can be painted or stained/weathered as you prefer. If you go with the look of unpainted weathered wood, the Traingineers recommend to stain the parts before assembly and gluing, as the glue may keep the stain from covering completely.
If you are painting the model, this may be done after the kit is fully assembled using brush, airbrush, or spray cans. Board fences were typically whitewashed; some post-assembly weathering may also be desired.
Do take your time and test-fit parts before assembly and please allow two or three evenings for the assembly and painting of this model."