Can't see where to copy the piece of code
Maybe it is good to know your platform/OS and what steps were tried already.
But as generic suggestion - there are available Knowledgebase articles:
After adding/installing extension for Google Chrome browser -> should be visible certain place to add "authorization code" into it. And such code should be available under F-Secure KEY UI (settings -> general / autofill settings -> "only browsers" and not as 'system autofill' option probably).
Running Windows 7
I've now managed to copy code to Chrome and authorise the extension, however, althought the Key icon appears in the logon fields, it does not trigger the display of the Key passwords from the Key listing.
I'm not too experienced with recent F-Secure KEY Builds and its autofill functionality.
But, probably, list of passwords will be visible if there is any entry with 'URL' for current website/page. It is kind of prevention against phishing maybe; and part of autofill-functionality for proper website and password.
Otherwise - possible to try 'system autofill' option under Settings and doublecheck what will be after "CTRL+F2" under field. Does entries are visible?
OR did you mean that entire form is 'white background' with no information? While it is expected that there should be something. And it is not possible to use steps like:
No - But when you ckick the blue Key icon in the password field, it does nothing!
You should have downloaded the latest version(presumable 4.9.56)
It works ok(chrome+key extension) at least with windows 10,in the key settings choose "autofilling used with browsers"