This only applies if you are using the Secure version of PDF Embedder.
If you have the 'disable right click' option selected, but this doesn't seem to be effective, then most likely your PDF isn't uploaded in secure mode. Please see the instructions on how to turn on secure mode and upload the PDF again.
When you are logged in to the site as an admin and view the page containing the PDF, you should see a 'secure' marker in the toolbar if it is displaying in secure mode.
If you right-click on the embedded PDF and Inspect Element, maybe you can see the direct URL of the PDF file. This might be disconcerting since you expected the 'secure' PDF to be obscured.
However, take a look at the URL. If it does not contain 'securepdfs' then it has not uploaded in secure mode, so please see instructions above and try again.
If it does contain 'securepdfs', then copy the URL to the clipboard and try to access it directly. You should see a '403 unauthorized' message - which is great, since the PDF is supposed to be protected and only visible within the viewer. If you can downloaded the PDF direct then that's a problem, and indicates something is wrong. On non-Apache servers, extra work may be required to ensure the 'securepdfs' folders are protected against direct access. For example, see a typical configuration required for nginx.