Honestly: don’t use Zotero. You get what you pay for, and Zotero is free/open source[1]. I do use Zotero to maintain a shared reference list with one collaborator, but it is painful to use compared to Bookends. Bookends was released in 1984(!!!), yet still gets monthly updates by a super supportive developer, Jon. Bookends fully supports extracting annotations from the PDFs it manages — AND you can use Applescript to copy these notes (with citekeys linked to page numbers) directly into Scrivener. It does a thousand other things better than Zotero (managing keyword lists, detailed duplicate management, SQL querying, a very flexible UI, amazing format and import editor, a version for iOS with full sync, including annotations etc. etc. etc.). I see Scrivener and Bookends as critical tools for a fluid academic workflow, and each is carefully crafted by a dedicated paid developer. Most pertinently to this thread, Bookends works flawlessly with Scrivener. Or if you really want to save money, probably take some time off writing, learn to code, and contribute to build a better Zotero…
[1] Zotero is currently going through a major transition. V5 broke most tools that were built for V4, but V5 is itself transitional. Firefox killed its extension system, and therefore Zotero will have to completely rewrite everything for V6. Most bits of the Zotero ecosystem were built by volunteers, who have other commitments and this will impact how fast we get the tools to work. And as Keith mentions, “This is still in early stages of development, so proceed with caution when using this in a production application.” is not a tempting prospect for a developer like Keith.