Add a feature to a website to provide a means to download custom-watermarked PDF files

This is how I envision this, but I am open to other ideas: The website owner is provided a means to post the following to the website: 1) a zip files containing PDF which have been renamed to .pdfX, PDF files, and other files and directories 2) a specification on the size, placement, and transparency of the watermark 3) a list of authorized users which includes: a) The User’s name b) User’s Company name c) The User’s Email Address d) A short (6-digit) passcode e) The name of the ZIP file(s) the User is authorized to download f) Expiration date Users can then open the website, enter their name and passcode, and then be able to download a copy of the zip file (matching the name in e) above) where the all *.pdfX files in the zip file have been modified with a watermark containing the User’s name and the User’s Company name and renamed to *.pdf. Other files in the ZIP should be unmodified. The website will no longer download the zip file after the expiration date. The website is hosted by bluehost, and developed in WordPress and Elementor I will also need a short explanation of how this code works, and how to integrated it into my website. This job is budgeted and will be awarded. Looking for a completion within 2 weeks if possible.