The 2000 and 1004 error often happens in conjunction with the Steam Client.
If this error happens, you should contact the community there.
Otherwise jump into this topic below. There are some details on how to bring the game to Origin. This is the client of EA and will be officially supported here.
Well, thank you for just taking your time to reply.
I've scrolled a bit through your linked topic, so I thought I could install that origin client. But I don't know where exactly to get the "CD key". In Steam --> Spore I haven't found anything about a CD key.
Did not you receive an bill via email from Steam, where this is written. As I said for this you have to contact the support of Steam.
September 2019 - last edited September 2019
I did receive a bill via email, but there is nothing mentioned about a CD key.
Alrighty then. I'm gonna contact the Steam support. But thank you a lot for you help, much appreciated!
EDIT: All suggested supporting addreses on Steam lead back to Answer HQ. Steam itself seems to refuse giving support.