Boot partition contains "config" file full of nonsense. Also, the image won't work on my RPI 3 B+

Hello, I'm just trying SamplerBox for the first time. Does the image file simply not work on the B+ at all? I've followed the procedure exactly. It simply does not boot up to the login screen at all. The power LED just blinks.

Also, whenever I check the boot partition, the config file is filled with unintelligible nonsense when I open it with Notepad. I don't know what is responsible for this. I'm using Etcher.

I can provide additional information if needed.

Thanks for any help!