Open the required file in viewer which you need to save as PDF.
Next, follow the steps for navigating to File Viewer More Options.
In the 'More Options' menu, select 'Save as PDF' option (under 'Print' category) to download files (in any format supported by Asite File Viewer) including markups if any and save it to your local folder in PDF file format.
Next Article: View Attachments & Associations on a File open in Viewer