If for any reason that you find that the browser connector isn't working, you can always download a citation manually.
To do this, you need to find the option to save an RIS file format of the citation. This is often under an option for "Export," "Save Citation," or "Download Citation." This often opens a new box, tab, or page that gives you a variety of options for saving the citation file. The option that Zotero needs is the "RIS" format.
Once it's downloaded, you'll need to open the file to import it to Zotero. It's often useful to already have the Zotero App open in order to do these step seamlessly.
Zotero will automatically recognize the file and ask if you want to import it into your Library. Select yes and it will automatically appear in your Zotero Library.