You should now have the updated version.
If you are unable to enable *Developer mode.* You can always delete and reinstall the extension.
Right-click on the Chartnote extension and select *Remove from Chrome.*
To reinstall, go to<https://chrome.google.com/webstore/detail/chartnote/bkfagmnilllacgphpepbdmialglfjjpi>
and click "Add to Chrome"