Custom Fields

As per this page:
https://www.imagely.com/docs/custom-fields-v2-0/
Custom fields in NGGalleries still work.

However, nothing displays from any of my custom fields which are things like ‘size’ in the images section of the gallery.

This plugin is no longer updated in any meaningful way – https://ww.wp.xz.cn/plugins/advanced-custom-fields-nextgen-gallery-field-add-on/

Is there a method for adding custom fields to templates?
Or is there better syntax for the custom fields plugin I posted above which currently uses this:

<?php echo $image->ngg_custom_fields["size"]; ?>