I am Argentine and I live in San Diego, what papers should I bring with me? Do I have to make an appointment or can I go directly?

You need official government ID (CA or US govt) Proof of residency (recent utility bill or something addressed to you) and your green card or whatever papers you have instead of a social security card, that allow you to legally live and work here. That being said, OctaPharma is the shadiest of all the plasma donation centers (which is saying something,) so I wouldn't be surprised if the other answers are true and they won't ask for anything but ID, BUT technically are are supposed to have the things I described. 😉

I.D. and proof of address. That's it 🙂

I didn't even need my Social Security card Just my ID..

You can walk in. You need an ID, social security card and proof of address. 1st time takes about 3 hrs...