Update from above:
I’ve figured out how to get Responsive Lightbox to work with this plugin.
I’m using Responsive Lightbox ver. 1.6.5, and using the Fancy Box option. In the Responsive Lightbox general settings, check ‘Add lightbox to WordPress image galleries by default.’ and ‘Try to force lightbox for custom WP gallery replacements, like Jetpack tiled galleries’. Set the loading place to Footer and check ‘Enable to load scripts and styles only on pages that have images or galleries in post content’ so not to load in non-gallery pages/posts. In the Lightbox Settings, I’ve got ‘Scrolling (in/out)’ set to ‘NO’.
In the WordPress Media settings, at the bottom of the page, where the Image Gallery Carousel settings are, un-check ‘Enable Carousel’ and check ‘Tiled Galleries’. These settings give me a lightbox gallery, with the mosiac tiled thumbnails in the post content.
You might have to edit each gallery to link to Media file, instead of Attachment page. And check to make sure the Gallery settings type is set to Tiled Mosiac.
Hope this helps folks.