Centering Load More Button in Collection List for Web Design

Using https://www.relume.io/components/portfolio-9 and https://finsweet.com/attributes/list-load to load more. I've tried a million different ways but can't get my own centered button to load more as it needs to be in the collection list - but I can also not get the native 'next' button to be on a full row below the gallery. Any ideas?