Make sure you have the requirements installed on Win 11 before you use it.
Java etc …
The details are all here Watchface Designer
There are some interesting bits of info in this thread and I didn’t see the point in re-posting information. Both beta and last prod app version are in this thread as well.
I believe WatchFaceDesigner_v0.14.1.zip is the last prod version and it is also linked in that main thread.