WordPress by default saves all media files like images, videos and PDFs under the directory called upload. BSK PDF Manager have the ability to change default upload directory in WordPress.
By default BSK PDF Manager upload files to upload/bsk-pdf-manager, so the file you upload can be viewed with the URL
http://www.yoursitename.com/wp-content/uploads/bsk-pdf-manager/newsletter.pdf
In case if you have selected the check box Organize my uploads into month- and year-based folders available under Settings > General Settings > Upload then a file uploaded on July 2019 in your site can be viewed with the URL:
http://www.yoursitename.com/wp-content/uploads/bsk-pdf-manager/2019/07/newsletter.pdf
BSK PDF Manager support change upload folder to anywhere under your site.
Check here for more about change default upload folder