BSK PDF Manager Pro support display your PDFs in multiple columns.
To use this feature you need enable it in setting page first.
Navigate to your site Dashboard -> BSK PDF Pro -> Settings & Update> and click Multi-column Layout tab, there you can enable multiple columns by check "Enable multi-column layout".
With this checked it means the global switch for multiple columns is on. To display your PDFs in columns you still need call right shortcode with right columns parameter. Such as [bsk-pdfm-category-columns id="1" columns="2"] to display all PDFs under category of id = 1 in two columns.