If you want to apply an effect to an existing recording, you need to make sure you follow these steps: https://www.nchsoftware.com/voicechanger/kb/1609.html
When you connect Voxal to another program, Voxal must be opened prior to the program that you are using the effect in. Close both programs, open Voxal, then open the program where you would like to apply the voice effect.