We had another user with a similar issue who found that if he deleted the directories with the wrong name then SAM would work: Authorize Steinberg Activation Manager - #27 by MilosBetko So can you try deleting the whole C:\Users\MiloĹ directory?
As you can see from the timestamps in the screenshots in his thread, the incorrect user directories were quite old, so I suspect it is not Dorico that is creating those incorrectly-named users, but it does look like Dorico might be confused that they are there. I wonder if there was once a Windows bug that generated those directories.
Also, can you let me know what exact version of Windows 10 you are using, as far as language is concerned? We can certainly try creating a user with a non-Latin username, but it may be that the result will depend on the OS as a whole.