The problem you are talking about looks like your firewall blocking the connection between the editor and the kiosc app.
It often happens with windows 11, and maybe Microsoft decided to make their windows 10 firewall follow the same rules.
You can or turn off your firewall, to check if it does fix the problem or add the Kiosc editor to the firewall white list.
In any case, it's possible to transfert the file from your computer to your android device by connecting them via USB.
To know where the file is stored in you computer just click on the 'folder' icon displayed on the "save as" Kiosc editor's windows.
Then copy paste this file to your android device, going into
For android 11 and over:
Android/data/nl.visualproductions.kiosc /files/documents/Visual Productions / KIOSC/ App data
Up to android 11:
Android/Visual Productions / KIOSC/ App data
Once your *,kiosc file will be into this folder, you will be able to select in in kiosc.
Enjoy