I see the description telling me recently accessed files are downloaded for faster access (makes sense) but when does that downloaded copy get deleted to get the space back (sometimes you might access a large file on the cloud drive.
Any time you access iCloud with the Mac , it synchronizes with it. Exactly when the schedule is to do it automatically is unknown.
I have a Mac that is off all the time. I use it as print server only. When I turn it on maybe once a month, iCloud Drive files won’t be synchronized of course and nothing happens until I click the iCloud icon in the sidebar. Then it starts to synchronize.