Long-term Outlook users have probably noticed that they can’t attach files in events created as Teams meetings. Teams like cloudy files, not email attachments, so if you want to send some important information along with a meeting invitation, you can include links to the data or paste it into the body of the invitation. And once the meeting is created, you can share files with meeting participants, which is really the Teams way of getting the job done.
https://office365itpros.com/2021/01/07/share-files-teams-meetings/
