There are multiple options during, and after, the meeting to see the attendance or download a report. Here is a resource that will walk you through the process.

https://support.microsoft.com/en-us/office/view-and-download-meeting-attendance-reports-in-teams-ae7cf170-530c-47d3-84c1-3aedac74d310?ui=en-us&rs=en-us&ad=us