Hi David,
Thanks so much for reaching out and for your interest in our products!
You can manually add orders through WooCommerce for orders that are taken over the phone. You can also create a WordPress user for those orders and use the User Switching plugin to create the order for your customers on the front-end.
In general, tickets are emailed to your users, which can be scanned with a QR code. There is the option to print out a ticket for check-in that way as well. For users without an email address, they can provide their name at the event and can be manually checked in from the backend of your site, or checked off a list of attendees.
You also have the option to require users to log in before they purchase tickets/RSVPs if you want.
Let me know if you have any other questions!
Thanks,
Jaime