To maximize uploads from your guests, consider implementing one or more of the following:
Include your QR Code on your event's welcome signage.
Add your QR Code to event materials such as table cards, menus, agendas, and invitations.
If you have a large screen, like a projector, occasionally display your QR Code on there.
Include a mini QR-Code card in your guests' take-home bags, if applicable to your event.
Have the MC introduce GuestCam and make multiple reminder announcements during the event. If you have the MagicFind add-on, let them include it in the announcement.
Let your event helpers (if your event has any) inform & remind guests to scan & upload
Share the gallery's link after the event for guests who couldn't scan the QR code.