Mac OSX and Windows incompatible

Hello. I write with Scrivener on the Mac and now also on Windows.
I have installed the latest versions on both platforms.
I save the project in the dropbox so that I can synchronize it under iOS.
That works.
The Windows version is the 1.9.16.0 from Nov.2019
If I want to open the project from the dropbox I get an error message that the version is outdated and the repository is newer and I should update
Unfortunately there is no update.

If I import the project with Scrivener under Windows, all texts are empty.
Nothing is there.

Is Scrivener incompatible with itself?

Yes, you can work on a project using either the older version for Windows or a Mac. Here is a link to the knowledge base article on the matter.

In order to edit the exact same project on both machines, you would need to switch to using the public beta version for Windows. This will be the ideal option if you wish to make use of the new metadata features and so forth, from the Mac.