To view or export the check-in attendees, you can go to Management >> Check-In

If you have a Session Check-In you can use the Event dropdown filter to filter according to your session.

To quickly view the number of people check-in, you can hover your mouse at the pie chart and you can see the number of check-in for your event/session.

To export the check in list, you can click on the Action button  and choose Export