Figure: Form for adding a security key
On this page, you can activate a Yubikey security key. Insert it into a USB port of your computer and touch it. The entry will then be simulated in the field One-time password. With a click on Submit you will be redirected back to the page Two-factor authentication and the security key is displayed with its ID in the overview there.
If you add further security keys, one more field is displayed, where you additionally need to enter an existing security key.
Figure: Form for adding a security key