V-Ray only renders the raw light by default - you need to process the light in the same way you might edit a photo.
The v-ray frame buffer has various post processing controls that will allow you to tweak the image to suit
Generally if I need to do this sort of thing I go back to my studio photography training. I create a seamless background and light it independently of the product so I can get a white background. Sometimes I’ll will give the material on the background illumination but you have to be careful with that because it can blow out the shadows. Then I export the image and in my image editor I remove the background. That’s easily done by selecting the background color and deleting it.
Here’s a quickie example. I didn’t put much effort into rendering the product because I mostly just wanted the shadow for the example. This is before deleting the background pixels.
I would normally let the render run longer and denoise the background more.
And here I’ve combined that image sans bacckground with an image of old paper just to show that you can see through background
I set up the model with a seamless background. The object you’re rendering could be mounted on a “wall” instead if that’s more appropriate for the shadows you need.
