I’ve been trying to find an answer to a basic question in this thread:
Does Scrivener support cross-platform editing of a Scrivener file?
I have Scrivener on Windows and want to sync to dropbox to edit with my iphone or ipad. Does the syncing work with Scrivener on Windows? And will editing between Win/iOS cause issues?
Yes.
No.
Given that you’re using Dropbox, don’t open the same project on more than one device at a time (no matter on what platform) and let your projects sync before opening them somewhere else.
Thank you! appreciate the quick response. 
By the way, here is the full answer on this question, from our FAQ. There are a few things to be wary of, but most are understandable, like missing fonts, or using platforms-specific technology such as shortcuts/aliases, or WebArchive/MHT files.
The licenses are platform-specific, but the file type is cross-platform compatible. You can open Scrivener files on any device you have Scrivener installed.
With the new Scrivener 3 for windows, are the windows and Mac versions compatible for editing the same projects?