It would appear phone and direct emails to Tech support are no longer available :-( Sometimes there is a “chat” button that might be useful, probably during their office hours, but not sure what those are, or in what time zone? It is there right now (10:30am, CST). Or submit a “ticket” to them via the “submit and enquiry” button.
https://support.clarivate.com/Endnote/s/?language=en_US
or hope they contact you as a result of your post here. There are some “common questions” link there too.