In Scrivener's "Project" panel click the "Edit" button. The Settings gear will appear at the bottom of that panel. Use the command to set up Dropbox. You can choose a single Dropbox directory to be the location for all your .scriv project files. (They are really "packages" full of files.) You have to use the same folder on the Mac side, obviously.

Stephen Zeoli wrote:

Bear Notes looks interesting, but it also appears to offer much of the
same functionality as Ulysses.

Another option could even be Scrivener, which has a Windows version in
addition to Mac and iOS. It is supposed to sync through Dropbox, though
I'm still trying to figure that out.

Steve Z.