The Karaoke Anywhere app will play standard MP3+G zip files. These contain two files. One must be an mp3 file and the other must be the accompanying cdg file. The zip file cannot contain any other files or folders.
It seems from what you describe, the file you are attempting to play through Karaoke Anywhere is an MP3 file but that it either does not have a proper CDG file, or the MP3+G zip file is not in the proper format.