Installing the Kodamail extension
Clicking the big green button will take you to the chrome web-store where you can download and install.
Once installed it will appear like this in your chrome extensions page: (chrome://extensions/)

The green arrow above shows the extension is switched on, (dragging the blue bar to the left disables the extension).

At anytime you can disable/switch off any extension by dragging the icon to the left as above, be sure to reload gmail afterwards so that it takes effect.
It's possible that extensions can conflict with each other, if you suspect that is the case then switch the other extensions off and reload.

You can also remove any extension by clicking the appropiate Remove button.

We use Google "one tap sign in":
First you have to give permission:


Once you allow one tap sign in at the Google pop up, the sign in process is simple.

If you are signed into multiple Gmail accounts you will be asked to select an account, otherwise sign in will be automatic.



Installation issues:
Ad-blocker programs can prevent the pop-up from Google appearing.
It's import to allow pop-ups from Google as Google will present a pop-up window during installation asking you to allow Google sign in.
Go to chrome://settings (Copy and paste 'chrome://settings' into the url bar).
Scoll down page to 'Advanced'
Click on 'Content settings' then 'Pop-ups and redirects'
Allow or add 'https://mail.google.com:443' to list of allowed pop-ups.

This link will help you manage pop-ups in google chrome:
Allow pop ups in chrome

Sometimes the extension will not fully load - the kodamail icons don't show for example.
1. Delete your cache then reload Gmail.
2. If clearing your cache doesn't help then close all chrome windows, wait a couple of minutes to fully close (this can be seen in Task Manager)
and then re-launch Chrome, to restore all previous tabs click on "Customise and control Google Chrome" in top right:

then click "History", it will show recently closed tabs - click to restore tabs.