1. When you try to sign a document with an ID-card and get an error message "Signing failed. Please check that you have allowed ID card signing in your browser settings (Settings -> More tools -> Extensions). Have a closer look from here: http://id.ee/?lang=en&id=36600."
Run Google Chrome and on top right corner click on the icon which reminds three (3) dots.
Choose "More tools" -> "Extensions"
Make sure your ID-card signing is "Enabled".
2. You might get some help also from here: http://id.ee/?lang=en&id=36639.
3. Or you might need to update your browser: https://www.computerhope.com/issues/ch001388.htm.