Collaborate on a shared Freeform board on Mac
When you collaborate with others on a shared Freeform board, you can make edits and see if edits were made while you were away. Changes are saved in iCloud, so everyone with access to the board sees the latest version whenever they open it.
Open a shared board:
If you shared the board: Select the board in the Freeform app
on your Mac.If the board was shared with you: Click the link you received.
After you open the board, it appears in the Shared category in the Freeform sidebar.
If the owner has given you permission, edit the board.
All participants who have the board open can see the changes you and others make in real time.
When you share a board using the Messages app 
you can see who made updates since the last time you viewed the board in Messages. See Collaborate on projects with Messages.