Although the screen shot makes this look like a DOS program, it will only run in a Windows CMD/DOS window.  Here is a description of the program straight from the readme file included in the archive:

This small tool belongs to the group of utilities supporting the emulation of the good old C64. To be more precise, it helps you to reuse your old tapes recorded with the C2N (Datasette) of  Commodore and full of programs for the C64. All you have to do is to record the C64-tape with your soundcard and your favourite sampling-software (for example the sound-recorder of Windows 9x).