When I edit something in my Dorico project and wait for more than a minute, I would expect to find a file with a “Date modified” that is after the time I changed the project. I checked my (custom) project folder and the project backup folder, but both still contain the files of the last manual save. No trace of an autosave file…
The Project backup folder stores a copy of the file each time you manually save. The AutoSave folder does something different: it saves at timed intervals, and once a project is successfully closed (via usual means) it is emptied.
The Autosave path is not customisable (at least not without editing the preferences.xml file outside of Dorico).
It’s a hidden folder found at ~/Library/Application Support/Steinberg/Dorico 4/AutoSave
(Copy and paste that string including the ~ tilde into Finder > Go > Go to Folder…)