angelika7775 The Redeem a Code button worked for me just now. So did Register a Game, which is what you'd use for the base game and any expansion or stuff packs. (The other is for Store content like worlds and bonus items.) So please try again now. If it still doesn't work, try a different browser.
If you still can't get the site to load by Monday, when EA community managers should be available again, please post back and let me know so I can flag the issue.
Whatever you do, do NOT try to register any Store content in the EA App. This will likely use up your codes without adding the content to your account. It is however fine to register expansion or stuff packs there, although sometimes the Store site won't recognize you own that content.