I am sorry, I will try to describe this more to improve understanding.
We have noncommercial photo sessions with models.
I want to use IMS, with disable store enabled, to show them published photos in a gallerie.
Now, because this is a noncommercial cooperation, I would like to allow them full sized photo download.
As additional plugin feature this could be “Put to download basket” instead “Ad to cart” (an idea)
and, in reference to topic question would be: how to allow user a full sized download if there is no purchase with payment via IMS plugin?