Via the api you can influence the popup behavior. The documentation is excellent.
And indeed, this is a very powerful lightbox script.
You have to set „title and description“ to permanent and as an overlay.
The title gets its own bar in the markup, and is placed on top. In the bottom bar, the alt attribute is displayed first, and below that, the description. Enfold takes the description from the Media Library, but can also change it permanently here in Masonry.
I would prefer a custom input field here, so that you can use the same image several times with different labels.
As you can see, you can even have the arrows prev./next inside the lightbox.
Show title and description as overlay is better if you don’t want to display anything below the thumbnails in the frontend.
Reason: the calculation of the height of Masonry items includes this height, even if they are set to display: none.