If you still cannot control the Mac and it has 'Start with system' turned on: Turn 'Start with system' off on the Mac you want to control (Remote Control Unattended Access). Restart that Mac (just in case). Open TeamViewer again (still with 'Start with system' off). TeamViewer Host for Mac is used for 24/7 access to remote computers, which makes it an ideal solution for uses such as remote monitoring, server maintenance, or home-office access. The app is a Servers & Network software developed by TeamViewer. Install TeamViewer Host for macOS on an unlimited number of computers and devices. As a licensed user, you have access to them all!
Teamviewer For Macbook
If you are starting TeamViewer on your Mac running macOS 10.15 (Catalina) for the first time, you will be prompted with the following dialog:
By default, all permissions are set to Denied. Please give permission to the system capabilities manually to use TeamViewer as desired. If you want to allow remote access to your Mac, Screen Recording and Accessibility are required at a minimum.
To allow the access, click the buttons shown in the dialog. Eg. click Open Full Disk Access Preferences… which will bring you to the Full Disk Access section of the Privacy pane, inside the Security & Privacy preferences:
For the Accessibility access you will need to click the padlock icon in the lower-left corner to make changes. You will be prompted to enter the credentials of an administrator account to continue.
Put a check next to TeamViewer to grant it access:
Teamviewer Mac Os Sierra
Click Later to continue. Repeat the same for Screen Recording and Accessibility. Those are required to control your Mac.
Click again on the padlock in the lower-left corner to prevent further changes.
Now you can close the Security & Privacy window. The next time you want to receive an incoming connection with TeamViewer, the person connecting to your Mac will be able to see and control your screen.
The permission status can be reviewed under Help -> Check system access at any time.