I have followed these steps while installing the gnome extension of chromium in Ubuntu 20.04.
As per their documentation ran a command to install chrome-gnome-shell
sudo apt-get install chrome-gnome-shell
Still while loading the gnome-extensions page, it is showing error that "Although GNOME Shell integration extension is running, native host connector is not detected. Refer documentation for instructions about installing connector."
Can anyone tell me how to resolve this issue in steps?
Probably this is because you are running Chromimium as a Snap. There is an open bug in Launchpad about this, that appears to still be happening in Ubuntu 20.04:
https://bugs.launchpad.net/ubuntu/+source/chromium-browser/+bug/1741074
The easiest solution would probably be to use another web browser, not in a Snap.