When a ticket buyer have completed the purchasing process s/he lands on a "My tickets" page showing the acquired ticket(s) for the event including a link to a Ticket PDF.
S/he also receives an email with a link to this page.
On the My tickets page there are also options to forward tickets and a transactions overview with the option to download the invoice, if one have been issued.
If the ticket buyers have bought multiple tickets of the same ticket type, the tickets are shown in the Manage tickets view with the option to forward the ticket.
Each additional ticket of the same type needs to forwarded and accepted by someone with a user profile to be valid for check-in. As an organizer you can find any not forwarded tickets on Manage event > Registration > Check-in.
How do I handle check-in at the event?