When using Chrome you will click on ‘Share screen’ in Connect4 then be shown a window similar to below showing the screens connected to your computer.

To share screen, click on the box of the screen you want to share then click Share button (bottom right corner).

The error "NotAllowedError" can occur when trying to share your screen using Chrome without doing the above.

To not have this error, make sure to the Share button is not gray as shown below as that shows the screen share has not been selected. Upon clicking on the screen to share, share button will turn blue indicating it is active.