How to change a post item html layout

In order to change html layout or add an element to a post item template You need to copy the item template file from the plugin (.../wp-content/plugins/posts-grid-builder/templates) into your theme(or child theme) to folder ‘posts-grid-builder’(.../your-theme/posts-grid-builder). Now the copied file from the theme will be taken as a template and it can be edited.