Press Return to send the message.
When someone edits the file, you see updates at the top of the Messages conversation. To return to the shared project and see changes, click an update.
You can also collaborate on a project when you’re in another app, including the Finder, Reminders, Notes, Safari, Freeform, Keynote, Numbers, Pages, and supported third-party apps.
Note: The process for inviting someone to collaborate depends on the app.
Go to a project: In the conversation, click the shared project. Or click in the top-right corner of a conversation, scroll to Collaboration, then Control-click the shared project and choose Share.
When you share the project, you can share it with new participants or the same group.
If you Control-click a shared project in the conversation, you can also do any of the following:
on your Mac, select a file or folder you shared from iCloud Drive, Control-click it, then choose Manage Shared File. See on your Mac, select a note or folder you shared, then click the Collaborate button. See on your Mac, click Shared in the sidebar, double-click a board, then click the Collaborate button. See Manage downtime in Screen Time on Mac