Check to see if the article request is caught in a never-ending loop: look in a lower corner of the webpage, to see if it’s constantly requesting the article from the publisher, then jumping to another page, then jumping back to the publisher, and never getting a chance to load the article you want. If this is happening, it is probably caused by Zotero, the browser-based bibliography manager. Disable Zotero by going to “More tools” -> “Extensions” (Chrome), “Add-ons and themes” (Firefox), or “Extensions” (Brave or Edge), and toggle off Zotero. Try again; the file should now get a chance to download.
