If you need to use an external speaker for your event, then you can easily connect a Bluetooth speaker to the iPad running the Snappic app.
Connect the speaker to the iPad.
Enable the Bluetooth function in the settings menu of the iPad and search to connect to your Bluetooth Speaker.
Connect the speaker to your event.
Once the speaker has been connected to the iPad, then open your event on the Snappic app. Tap on the "Start Photo Booth" button and then you will see the camera settings, as well as, two other tabs -"Filters" and "Accessories". Click on the "Accessories" tab and then on the Airplay icon as shown below.
You will now be able to select between your iPad or your Bluetooth Speaker as the sound output source. You can also adjust the volume by moving the slider.
Once you are done you can tap on "Start Booth" at the bottom of the iPad screen and start your event.
Please note: if your speaker does not show up on the pop-up (as seen above) you can do a quick check by accessing the settings menu on the iPad to ensure that you have allowed Bluetooth access to the Snappic app.