The Zotero beta reader does not store annotations in the PDF so Zotfile can’t see the annotations. You can force Zotero to write the annotations to the PDF (with a PDF open in the Zotero viewer, select File->Store annotations in file), at which point you can no longer edit them in Zotero. However, other changes to the Zotero beta have occasionally broken mdnotes so even with annotations stored in the PDF you may have to find other workarounds.
I believe the author of mdnotes has stated they’ll likely update once the new Zotero is out of beta. Zotfile’s maintainer has said they don’t really have time to work on it, and given that some of the main features of Zotfile are basically superseded by the new Zotero, I wouldn’t bet my workflow on Zotfile for the long-term.
The latest version of the Zotero beta does extract annotations and can then export them to Markdown. It’s pretty cumbersome (you have to select “Add Item Note from Annotations” from the Item Notes sidebar and then right-click export the note from your library), but it’s something.