Grid Posts

I’m trying to create a category page that shows the posts in a grid of 2 columns. I’ve followed the instructions at https://www.wpbeginner.com/wp-themes/how-to-create-a-grid-display-of-post-thumbnails-in-wordpress-themes/ but it’s not working out for me. Is there some conflicting code in the twentyfourteen theme that may be the issue? This is the page I’m trying to get in grid format: https://austintroya.com/blog/category/for-sale/