That's actually supposed to say "upload" folder, sorry about that.
When you've downloaded the .zip file, and extract it, you'll see two folders "upload" and "XML".
Open the "upload" folder, then place the files within on your server where your forum files are located (like where forum.php is).
Then, go to your AdminCP -> Plugins & Products -> Product Manager, click Add / Import Product -> browse to the "XML" folder and select the file from the vB40 directory.
That should sort it
Fillip