There is a high possibility that the web browser you are using has trouble with Google authentication. Please update your ColorNote to the latest version. If you still cannot sign into online backup even after the update, please follow the steps below.
- Install Chrome browser or Firefox browser.
- Open ColorNote and start sign-in process.
[Settings-> Online backup -> Sign in with Google account]
- Please set Chrome or Firefox as your default browser when sign into online sync.
- Sign into online backup