To require player input to advance each subtitle:
- Inspect the Dialogue Manager GameObject. Change the Display Settings > Subtitle Settings > Continue Button dropdown to Always.
- On the Input Device Manager component, tick Always Auto Focus. This will show a continue button with each subtitle. The space bar or enter (or clicking on the button) will advance the conversation. If you want to map another key to the continue button, inspect your dialogue UI's continue button. If it already has a UIButtonKeyTrigger component, set it to whatever hotkey you want to use. Otherwise add the component and configure it.