How do you do it? I close the Scrivener on Windows (laughable that I need to do that), and open my ALSO purchased copy on iPad (laughable that I need to purchase it again), make changes, and then close. Then when I open Scrivener on Windows it warns that changes were made when unsynced (???) and the changes are nowhere to be seen.
Do you guys realize it’s 2024?
To answer your question, I am one of the “anyone’s” and it works for me. Been doing it for a very long time this century, with full realisation it is now 2024. 
You mention nothing about setting up or using Dropbox, the only way you can sync between a Desktop and iPad.
For assistance, look in the Scrivener Manual, or at iOS / FAQs - Literature and Latte Support
Yes I have set it using Dropbox (laughable that I have to do that myself).
I’m doing a bit of laughing myself. Good luck.
What good is a support forum if it’s only populated by fanboys?
Hi js8. The first item I’d suggest reviewing is the Dropbox settings on your PC to ensure that your Scrivener projects are marked as “available offline” as per this Dropbox Support webpage.
That setting has caused syncing issues for other users on both Macs and PCs.
As for the workflow, you’re right that Dropbox syncing is not automatic. Nor does it happen immediately.
How long that will take depends on the speed of the internet connection, how much has changed in the project, and how many other demands are being made on the Dropbox servers at that time.
Here’s the workflow I use to keep my projects syncing without encountering any “conflicted files” errors:
I start with writing and editing on my computer. I can do this either by opening a File Explorer window on my PC, going to my Dropbox folder, and then double-clicking the Scrivener project to load it.
Or, I can use the File > Recent Projects or File > Favorite Projects list to open the project. I personally prefer using Scrivener’s File > Add Project to Favorites command when I create a project because the Recents list comes from the operating system. I’ve had updates to my computer delete all the items in that Recents list.
Then, I close Scrivener on my computer and monitor my Dropbox badge. If I’m working on a PC, that badge is in the lower-right corner of the taskbar.
I can hover my mouse pointer over the Dropbox badge to see if it indicates that all syncing is completed. Once I see that, I can power my computer down or put it to sleep.
On my iOS device, the first thing I do when starting to use Scrivener there is to tap the circular arrows icon to force it to download any recent changes from Dropbox. I’ll write and edit on the mobile device as needed.
When I’m done writing on my iOS device, I return to the Scrivener app’s main projects screen and tap the circular arrows button again to make sure that Scrivener uploads all its changes to Dropbox. I then swipe Scrivener off the device’s multitasking screen to close it.
If I’ve made a lot of changes, I’ll use the manual backup to save a ZIP copy of the project in my iOS device’s Files.app just to be safe.
That’s the typical workflow we recommend on this Knowledge Base article.
For those manual backups, we have this Knowledge Base article that explains how to create manual iOS backups.
Apple do not permit apps on their mobile devices to interact with the data in another app. That restriction prevents us from having the Scrivener app automatically back up the user’s information to the Files.app or Dropbox.app.
I’ll use that manual backup process frequently, just to ensure that any changes on the iOS device are retained if syncing goes awry.