Leave the authentication the same. If you have issues, you can report to us at firstname.lastname@example.org and go back to the prior settings. We will remove the prior setting if feedback is good.
EndNote cannot find the full-text 100% of the time. Success depends on meta data in the PDFs. Older PDFs may not have the meta data, and PDFs from publisher sites may be coded to work best with other citation managers. Remember, you can use drag-and-drop to attach full text in PDFs manually.