For Categories

First Slide add below

category_name=xxxxxx&posts_per_page=3
or
post_type-post&posts_per_page=3

Second Slide add below

category_name=xxxxxx&posts_per_page=3&offset=3&no_found_rows=true
or
post_type-post&posts_per_page=3&offset=3&no_found_rows=true

...and repeat

For CTP / Custom Post Type

post_type=stories&posts_per_page=3

Second Slide add below

post_type=stories&posts_per_page=3&offset=3&no_found_rows=true

Source: https://www.youtube.com/watch?v=qyrsAAKt_uU