Slowing down audio files, Amazing Slowdowner or something else?

macOS and Mac Apps


I need to be able to play certain parts of audio files in a loop and slow them down without changing the pitch. I thought this could be accomplished using Amazing Slowdowner which, reading on here, people like to use on their phones. I want to do this on my Mac and I'm having difficulty using Amazing Slowdowner. I can't seem to use either the edit boxes all the steppers to set where I want the loops to start and finish.

Is anybody using Amazing Slowdowner on your Mac? If so please could you take me through the process of setting up a loop and slowing it down?

Or is there another app I can use to do this? I may get Amadeus Pro for a different reason and expect it can do that, but have read that Amazing Slowdowner does a better job and is ideal for this specific purpose i.e. changing speed without changing pitch for the sake of learning to play songs.