If you've organized a Teams meeting, you can save a record of who's attended it. Here's how:
During the meeting, select Show participants and choose Download attendee list .
The report will download as a .CSV file that can be opened in Excel. Look for the file in your device's Downloads folder.
The .CSV file contains the name, join time, and leave time of all meeting attendees.
Keep in mind that, for now, the report must be downloaded during the meeting.
Only meeting organizers can download attendance reports. This option isn't available to other attendees.
This feature must be turned on by your admin. See Manage meeting policies in Teams for more info.