Here is an alternative I just found: Click on the journal webpage "Cite - Export citation to RIS". Zotero will directly identify the export. And then manually download the pdf.
@mingjun9900: Again, if you're having trouble saving, you need to report that with an example URL if you want us to fix it. Manually exporting to RIS is not a good workaround.
Click on the journal webpage "Cite - Export citation to RIS".
Zotero will directly identify the export. And then manually download the pdf.