To download an Attendance Report in MS Teams, locate and select your desired meeting in your Teams calendar. A new window with your meeting details will appear. Click on Attendance (circled in yellow below):
A new window will open providing an overview of participants. To download a list of attendees, click on Download (yellow circle below):
An Excel file will generate a list of attendees. Click on the Attendance report to view a list of participants (yellow circle below):