Whether you’re the owner of a shared spreadsheet or have been invited to collaborate, after you open the spreadsheet you can see the edits made by others in real time, hide or show editing activity, and more.
The number of people editing or viewing the spreadsheet (not including you) appears on the Collaborate button in the toolbar, and their names appear in the participant list.
When you receive a link to a shared spreadsheet, what happens when you click the link depends on the access and permission set by the owner, the Numbers and macOS versions installed on your computer, and whether you’re signed in to iCloud.
Click the link in the email, message, or post that you received.
If asked, sign in to iCloud with an Apple ID or follow any instructions that appear.
The spreadsheet opens based on the following:
On a Mac: The spreadsheet opens in Numbers for Mac or in Numbers for iCloud, depending on whether iCloud is set up on your Mac and you’re signed in; where you clicked the link (for example, in Mail on your Mac or on a webpage); and whether you have macOS 10.12 or later and Numbers 4.2 or later installed on your computer.
In iCloud.com on a Mac or Windows computer: If you’re signed in to iCloud.com in a web browser, the spreadsheet opens in Numbers for iCloud, and it’s added to your spreadsheet manager and to iCloud Drive.
On an iOS device with iOS 10 and Numbers 3.2 or later installed: The spreadsheet opens in Numbers on your iOS device and is added to your spreadsheet manager.
On an Android device, or an iOS device without iOS 10 and Numbers 3.2 or later installed: The spreadsheet opens in a browser where you can view but not edit it.
If you’re having trouble accepting an invitation, make sure you meet the iCloud and system requirements.
Open the shared spreadsheet.
If you previously opened the spreadsheet, look for it in the Numbers folder of iCloud Drive. If you don’t see the spreadsheet, click the link in the email, message, or post that you received, and if asked, sign in.
If you can’t open the spreadsheet, see “Accept an invitation to collaborate” above.
Edit the spreadsheet.
Edits you and others make to the spreadsheet appear in real time. Colored cursors and colored selections of text and objects indicate where others are currently editing. Move your pointer over a colored cursor to see who’s making the edit.
Do any of the following:
See who’s working in the spreadsheet: Click 
in the toolbar to open the participant list, which shows who has joined the spreadsheet and who is currently editing or viewing it.
The number of people editing or viewing the spreadsheet (not including you) appears on the button.
Follow someone’s edits: Click the colored dot next to the person’s name in the participant list. If you don’t see a colored dot, the person has the spreadsheet open but isn’t actively participating.
Hide or show activity (colored cursors or selections): Choose View > Hide Collaboration Activity or View > Show Collaboration Activity (from the View menu at the top of your screen).
Resolve conflicts: If you’re the spreadsheet owner and there are conflicts, you see a dialog. Choose the version you want to keep; if you keep more than one, the most recent remains the shared version.
If you see an alert on the Collaborate button 
in the toolbar, you can’t edit the spreadsheet until it’s online again. Check your Internet connection and wait for your computer to reconnect.
If you no longer want to have access to a spreadsheet that was shared with you, you can remove yourself from the participant list.
Click 
in the toolbar.
Move the pointer over your name, click the three dots that appear, then choose Remove Me.
Removing your name from the participant list removes the spreadsheet from your iCloud Drive. If you later want to access the spreadsheet again, you can use the original link to open it.
Note: Not all Numbers features are available for a spreadsheet that’s shared with others. See this Apple Support article for information.