Webconnector grayed out on mac / not available

I logged in to Teamwiever Management Conole on Web on Mac OS X Mojave and Safari.

When trying to connect the option for using Webconnector is grayed out and therefore not available. 

I do not want to install Teamviewer on that Mac and i also already tried to use Chrome and Chrome App (connections do not work and get closed immediatly after only showing a black image).

How to make Teamviewer Webconnector work on Mac ?