First, add someone as a scanner.
If you are the one scanning the tickets, you can skip the following guide:
Choose the desired event at the ‘Manage’ tab (a 'suitcase' icon at the bottom navigation bar).
Go to ‘Scanner’.
Hit 'Permissions'.
Scanner must register first using the mobile app.
Add a scanner by their phone number
Than, that's how the scanners (or you) actually scanning the tickets:
Choose the desired event at the ‘Manage’ tab.
Go to ‘Scanner’.
Allow using camera
Scan barcodes with the phone camera