Hi Ólína,
thank you for sharing your issue – I understand how frustrating it is when your login details are correct but you still can’t sign in on your PC. This often happens if the Apple apps on Windows need to be updated, the system time is out of sync, or the verification code expires too quickly. Please check that your Apple apps from the Microsoft Store, like iCloud or Apple Music, are up to date, make sure your PC’s date, time, and time zone are correct, and try signing in at appleid.apple.com. If the problem persists, contacting Apple Support directly is the safest option.
Just a gentle reminder: We have a dedicated community for English discussions over at discussions.apple.com. Since your post is in English, we warmly invite you to join us there for further discussions. Thanks for your understanding!
I hope this helps! / Ich hoffe, das hilft Dir weiter!
Take care and best regards / Alles Gute und liebe Grüße