Apple has introduced a security mechanism with macOS 10.14 (Mojave), which requires special access to be granted to remote control applications like TeamViewer.
And macOS 10.15 (Catalina) has strengthened the security and privacy even further and requires additional permissions to be given to TeamViewer in order to control your Mac.
Without this access, TeamViewer users connecting to macOS 10.14 or higher will only be able to view the screen but not control it with their mouse or keyboard.
And TeamViewer users connecting to macOS 10.15 or higher will additionally only be able to view the desktop background and the TeamViewer app, but not any other applications at all.
These additional permissions must be granted locally on the Mac and some of them require admin rights.
Please find the different how-to guides for the setup on Mojave and Catalina below.