Hi @knowmates,
To protect you pdf, I suggest you to use a PDF Embedder plugin. To learn more about it, please read the following article from WP Explorer: How to Embed PDF Files in WordPress.
Hope this article help you find the more suited plugin to your needs.
Don’t hesitate to share with us which plugin you have chosen. I’m sure it will help other users facing the same issue. By doing this, you will be making a great contribution to this forum, and we thank you very much for that! #SharingIsCaring 💪🏻
Best,