To assign multiple products to a media asset, it is only necessary to repeat the process of assigning product:

The Lightbox on your website would look similar to the following:

The customizable number of product photos allows you to specify how many products you would like to show at the same time without the user having to scroll to see them.

To achieve this design configured the following parameter:
visibleProducts(integer) – Configure the number of products that are shown simultaneously in the Lightbox when multiple products are linked to a photo (Number between 2-6)
Note: For more information, visit the list of available parameters to configure the widget's behaviour on your online store