Could not open downloaded openandromaps

there seems to be a problem (or two) with opening downloaded openandromaps. If I choose the zip-file nothing happens. If I extract the files from the zip-file, kurviger complains that there are no items.
I found out that kurviger has a problem with the filenames. They all contain the character sequence “.oam”. It seems that kurviger is not able to detect the extension because of that. after renaming the files kurviger managed to load the files

Android file browser displays a message about the expected file extension on each open action:

  • Map files (uncompressed) *.map
    (see the offline maps guide)
  • Map styles (compressed) *.zip