WordPress Plugin and Transcripts Module

I guess I’m missing a step or something. I’m running 2.9.5 and I’ve turned on the Transcripts module. But when I go to add a “Transcript” asset, it only gives me the choice of a Podigee Transcript in .txt format, but Auphonic is turning all of my transcripts into .vtt files.

Is there something I need to do to make the .vtt transcripts automatically populate in new episodes on WordPress?