If you wish to allow your audience to send in comments while holding your presentation so that you can get live feedback and comments throughout the session you can enable the Chat feature.
The comments will display for a few seconds in the Presentation view before they disappear and will not be saved for exporting afterward. If you want your audience to send in questions that don't disappear and are available for export, you can use the Q&A feature instead.
How to enable Chat
To enable chat, select the Interactivity tab on the right side panel. Click Interactivity, then Menti, then toggle Enable live chat:
Enable Chat while presenting
You can also toggle this feature on and off during your presentation by opening the presentation menu at the bottom left of the screen or simply by using the keyboard shortcut "E":