This members-only tutorial provides the steps to apply masonry on HappyFiles Gallery.
Step 1
Install and activate HappyFiles.
Create categories at Media Library.
Add a gallery showing images from your desired category/categories either in the Gutenberg editor or using a shortcode (like the following) in Oxygen's Shortcode component (set width to 100%).
The selected folder has no items.
Step 2
Install and activate My Custom Functionality plugin.
Connect to your hosting account using a FTP client and navigate to site's /wp-content/plugins/my-custom-functionality-master.
Create a file named masonry-init.js in the plugin's assets/js directory having the following: