Open Watcom: installer error

Open Watcom is an open source compiler http://www.openwatcom.org/

When trying to install

ftp://ftp.openwatcom.org/pub/open-watcom-c-win32-1.9.exe

it immediately fails (It refuses to install as my screnshot shows) . I guess it is
since it detects it is not being run in a true Windows systems.

However, if you open a terminal and run the installation program with a -s switch (i .e. open-watcom-c-win32-1.9.exe -s ) which skips the initial dialogs, installation is successful