If your video plays correctly in the canvas preview but the voices are out of sync with mouth movements in the exported version, the issue is likely related to the original video's frame rate. Your video probably has variable frame rate and CreateStudio publishes at 30fps.
To fix this, use Handbrake.
Upload your original video file and change the frame rate from "Variable Frame Rate (VFR)" to "Constant Framerate."
Import the newly generated version with the constant frame rate in CreateStudio.