Please note: The Safari browser had some problems working with Zotero for a year or two. This was an Apple issue. The Zotero folks are currently doing a test with the Safari 14 connector and a beta version of Zotero. I would not recommend adding the Safari connector just yet as users are reporting that it is still buggy and not functioning properly, although you will see it as a possibility to download.
On a more positive note: there is now a connector for Microsoft Edge.