Showing Captions when Interactive Button Clicked to Play Audio

I am working on Captivate 13.2.

I have a single-character block with a button. The learner clicks the button to listen to an audio file of a telephone interaction. 

For those persons who need captions, I need to add a caption file. Right now, I cannot find a way to display captions when the interactive button is clicked. I know how to add captions to slide audio, but not when clicking an interactive button.

Right now, the only way I can display the text for learners who cannot hear (or need captioning) is to add the full text in a hidden section that displays when the button is clicked. This makes the slide quite lengthy, and they have to scroll to find the next button.

Does anyone know how I can add captioning without having to include the audio script? I have a .VTT file with the same name as the audio clip. It didn't automatically pick up the captions as I expected.