Screens offers a few ways to share a remote user's active session, enabling you to see the user's desktop and activities and take control to assist with productivity or problem-solving.
You can share a session with a logged-in user by using the macOS Guest account. This method does not require the credentials for an existing user account on the remote Mac, but it does require a logged-in user to accept your Screen Sharing request.
In the remote Mac’s System Preferences, click Sharing.
Select either Screen Sharing or Remote Management, depending on your chosen configuration.
Click Computer Settings and enable Anyone may request permission to control screen.
In Screens Preferences, click the Macintosh tab.
Enable Prompt for Screen Sharing.
Connect to the remote Mac.
Select Ask to Share Screen.
The user on the remote Mac must accept your Screen Sharing request.
The remote user may deny your request, of course, resulting in a connection error.
If a user is logged into his macOS user account on the remote machine when Screens establishes a connection, Screens will prompt for a decision.
Ask for permission to share display: Prompts the remote user for permission to share his session with you.
Log in as yourself: Logs in and starts a background session with your own desktop, settings, etc.
If you have an existing Administrator account on the remote computer, you may connect directly to any active session without prompting logged-in users for permission or confirmation. This requires that Remote Management be enabled instead of Screen Sharing on the remote computer. For more information, see Configuring macOS for Remote Access.