Do I need to confirm place at King's????

Basically, I met my conditional offer of A*A*A to study at King's College London. It was my firm choice, and on results day I got an email from UCAS saying "congratulations, you got your place!" so I assumed I didn't need to confirm that I'm definitely going there on anything. However, on my 'King's apply' page, it says "You must accept your offer within UCAS and this page will update.". But I can't find anywhere on UCAS where I need to click "accept"! I can only see a "reject" button. So I'm confused. Is the King's website wrong, because King's was my firm choice and I'm automatically in if I meet the grades? Help!!!