Did the included copy of Raise Up Your Bat load properly when you first opened the game? If it did, you probably just didn't import them properly
If Raise Up Your Bat did load, are you sure you unzipped the custom maps you downloaded? Check the doc, I just added a gif that shows the exact file structure, it should work as long as you match that.
If Raise Up Your Bat didn't load, then there's something else wrong. Could you try running it from command prompt, and see if it outputs any errors? Ignore the 3 red extension errors, and 1 yellow icon warning, they're known and shouldn't ever cause issues. But any extra ones could explain the cause.