If you scroll down on the home page, or go to THIS PAGE, you will see a list of the categories for which tracks are available. You can start by looking for your selected music in Contest Ballads and Contest Uptunes. At the bottom of the page, you can change the "Display #" to all, and scroll through the alphabetized list to find your song.
Songs in those two categories are placed there because of feedback from the arranger of the song representing it as such. Sometimes, there will be reference to its contestability in the description, but not often.
The very BEST way to know if a song is contestable, and our recommended method, is to ask the arranger specifically. They can generally help you understand if it is a strong vehicle for your needs.