There are two ways to add a PDF file to your layout, depending on whether you want to merely provide a download link or to view the contents of a PDF file on-screen.
Sometimes viewers don't need to see the PDF file contents before they download, you'd rather just provide a download button or link. Use the following procedure.
On the WordPress admin panel, click Media.
Upload the PDF file by dragging it into the Media window.
Or click Add new and select the file for upload.
Click the file you added to open the Attachment details sidebar and copy the URL displayed there.
Close the Media Library.
Open your page in Beaver Builder and open the module into which you want to insert the link.
Enter the URL to the PDF in the appropriate field.
If you want to display the contents of a PDF in a viewport on your web page, you'll have to use a plugin. Use one that lets you insert a shortcode into your layout. Make sure you're happy with the plugin's responsive capabilities so the PDFs can be viewed on small devices. If you also want your users to be able to download the PDF they're viewing, make sure the plugin offers that as well.
See this article for information about where you can insert shortcodes.